1
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Dunstan MA, Manvell AS, Yutronkie NJ, Aribot F, Bendix J, Rogalev A, Pedersen KS. Tunable valence tautomerism in lanthanide-organic alloys. Nat Chem 2024; 16:735-740. [PMID: 38374454 DOI: 10.1038/s41557-023-01422-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 12/12/2023] [Indexed: 02/21/2024]
Abstract
The inimitable electronic structures of the lanthanide (Ln) ions are key to advanced materials and technologies involving these elements. The trivalent ions are ubiquitous and are used much more widely than the divalent and tetravalent analogues, which possess vastly different optical and magnetic properties. Hence, alteration of the valence electron count by external stimuli can lead to dramatic changes in materials properties. Compounds exhibiting a temperature-induced complete Ln(III) ⇄ Ln(II) switch, referred to as a valence tautomeric (VT) transition, are rare. Here we present an abrupt and hysteretic VT transition in a lanthanide-based coordination polymer, SmI2(pyrazine)3, driven by the interconversion of Sm(II)-pyrazine(0) and Sm(III)-pyrazine(·-) redox pairs. Alloying SmI2(pyrazine)3 with Yb(II) yields isomorphous Sm1-xYbxI2(pyrazine)3 solid solutions with VT transition critical temperatures ranging widely from 200 K to ∼50 K at ambient pressure. These findings demonstrate a simple strategy to realize thermally switchable magnetic materials with chemically tunable transition temperatures.
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Affiliation(s)
- Maja A Dunstan
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark.
| | - Anna S Manvell
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | | | - Frédéric Aribot
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Jesper Bendix
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Andrei Rogalev
- European Synchrotron Radiation Facility, Grenoble, France
| | - Kasper S Pedersen
- Department of Chemistry, Technical University of Denmark, Kongens Lyngby, Denmark.
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2
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Lavroff RH, Munarriz J, Dickerson CE, Munoz F, Alexandrova AN. Chemical bonding dictates drastic critical temperature difference in two seemingly identical superconductors. Proc Natl Acad Sci U S A 2024; 121:e2316101121. [PMID: 38547068 PMCID: PMC10998635 DOI: 10.1073/pnas.2316101121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/11/2024] [Indexed: 04/08/2024] Open
Abstract
Though YB6 and LaB6 share the same crystal structure, atomic valence electron configuration, and phonon modes, they exhibit drastically different phonon-mediated superconductivity. YB6 superconducts below 8.4 K, giving it the second-highest critical temperature of known borides, second only to MgB2. LaB6 does not superconduct until near-absolute zero temperatures (below 0.45 K), however. Though previous studies have quantified the canonical superconductivity descriptors of YB6's greater Fermi-level (Ef) density of states and higher electron-phonon coupling (EPC), the root of this difference has not been assessed with full detail of the electronic structure. Through chemical bonding, we determine low-lying, unoccupied 4f atomic orbitals in lanthanum to be the key difference between these superconductors. These orbitals, which are not accessible in YB6, hybridize with π B-B bonds and bring this π-system lower in energy than the σ B-B bonds otherwise at Ef. This inversion of bands is crucial: the optical phonon modes we show responsible for superconductivity cause the σ-orbitals of YB6 to change drastically in overlap, but couple weakly to the π-orbitals of LaB6. These phonons in YB6 even access a crossing of electronic states, indicating strong EPC. No such crossing in LaB6 is observed. Finally, a supercell (the M k-point) is shown to undergo Peierls-like effects in YB6, introducing additional EPC from both softened acoustic phonons and the same electron-coupled optical modes as in the unit cell. Overall, we find that LaB6 and YB6 have fundamentally different mechanisms of superconductivity, despite their otherwise near-identity.
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Affiliation(s)
- Robert H. Lavroff
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Julen Munarriz
- Departamento de Química Física and Instituto de Biocomputación y Física de Sistemas Complejos, Universidad de Zaragoza, Zaragoza50009, Spain
| | - Claire E. Dickerson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
| | - Francisco Munoz
- Departamento de Física, Facultad de Ciencias, Universidad de Chile, Santiago7800024, Chile
- Center for the Development of Nanoscience and Nanotechnology, Santiago9330111, Chile
| | - Anastassia N. Alexandrova
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA90095
- Department of Materials Science and Engineering, University of California, Los Angeles, CA90095
- California NanoSystems Institute, University of California, Los Angeles, CA90095
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3
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Stensberg J, Han X, Lee S, McGill SA, Paglione J, Takeuchi I, Kane CL, Wu L. Observation of the Superconducting Proximity Effect from Surface States in SmB_{6}/YB_{6} Thin Film Heterostructures via Terahertz Spectroscopy. Phys Rev Lett 2023; 130:096901. [PMID: 36930917 DOI: 10.1103/physrevlett.130.096901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 08/12/2022] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
The ac conduction of epitaxially grown SmB_{6} thin films and superconducting heterostructures of SmB_{6}/YB_{6} are investigated via time-domain terahertz spectroscopy. A two-channel model of thickness-dependent bulk states and thickness-independent surface states accurately describes the measured conductance of bare SmB_{6} thin films, demonstrating the presence of surface states in SmB_{6}. While the observed reductions in the simultaneously measured superconducting gap, transition temperature, and superfluid density of SmB_{6}/YB_{6} heterostructures relative to bare YB_{6} indicate the penetration of proximity-induced superconductivity into the SmB_{6} overlayer; the corresponding SmB_{6}-thickness independence between different heterostructures indicates that the induced superconductivity is predominantly confined to the interface surface state of the SmB_{6}. This study demonstrates the ability of terahertz spectroscopy to probe proximity-induced superconductivity at an interface buried within a heterostructure, and our results show that SmB_{6} behaves as a predominantly insulating bulk surrounded by conducting surface states in both the normal and induced-superconducting states in both terahertz and dc responses, which is consistent with the topological Kondo insulator picture.
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Affiliation(s)
- Jonathan Stensberg
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Xingyue Han
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Seunghun Lee
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
- Department of Physics, Pukyong National University, Busan 48513, Republic of Korea
| | - Stephen A McGill
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA
| | - Johnpierre Paglione
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Ichiro Takeuchi
- Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, USA
- Maryland Quantum Materials Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Charles L Kane
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Liang Wu
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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4
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Li YS, Borth R, Hicks CW, Mackenzie AP, Nicklas M. Heat-capacity measurements under uniaxial pressure using a piezo-driven device. Rev Sci Instrum 2020; 91:103903. [PMID: 33138600 DOI: 10.1063/5.0021919] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/07/2020] [Indexed: 06/11/2023]
Abstract
We report the development of a technique to measure heat capacity at large uniaxial pressure using a piezoelectric-driven device generating compressive and tensile strain in the sample. Our setup is optimized for temperatures ranging from 8 K down to millikelvin. Using an AC heat-capacity technique, we are able to achieve an extremely high resolution and to probe a homogeneously strained part of the sample. We demonstrate the capabilities of our setup on the unconventional superconductor Sr2RuO4. By replacing thermometer and adjusting the remaining setup accordingly, the temperature regime of the experiment can be adapted to other temperature ranges of interest.
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Affiliation(s)
- Y-S Li
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - R Borth
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - C W Hicks
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - A P Mackenzie
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
| | - M Nicklas
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden, Germany
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5
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Zhao C, Hu M, Qin J, Xia B, Liu C, Wang S, Guan D, Li Y, Zheng H, Liu J, Jia J. Strain Tunable Semimetal-Topological-Insulator Transition in Monolayer 1T^{'}-WTe_{2}. Phys Rev Lett 2020; 125:046801. [PMID: 32794806 DOI: 10.1103/physrevlett.125.046801] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
A quantum spin hall insulator is manifested by its conducting edge channels that originate from the nontrivial topology of the insulating bulk states. Monolayer 1T^{'}-WTe_{2} exhibits this quantized edge conductance in transport measurements, but because of its semimetallic nature, the coherence length is restricted to around 100 nm. To overcome this restriction, we propose a strain engineering technique to tune the electronic structure, where either a compressive strain along the a axis or a tensile strain along the b axis can drive 1T^{'}-WTe_{2} into an full gap insulating phase. A combined study of molecular beam epitaxy and in situ scanning tunneling microscopy or spectroscopy then confirmed such a phase transition. Meanwhile, the topological edge states were found to be very robust in the presence of strain.
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Affiliation(s)
- Chenxiao Zhao
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Mengli Hu
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jin Qin
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Bing Xia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Canhua Liu
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Shiyong Wang
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - DanDan Guan
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yaoyi Li
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Hao Zheng
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Junwei Liu
- Department of Physics, Hong Kong University of Science and Technology, Hong Kong, China
| | - Jinfeng Jia
- Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
- Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 200240, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
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6
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Robinson PJ, Munarriz J, Valentine ME, Granmoe A, Drichko N, Chamorro JR, Rosa PF, McQueen TM, Alexandrova AN. Dynamical Bonding Driving Mixed Valency in a Metal Boride. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Paul J. Robinson
- Department of Chemistry and Biochemistry University of California Los Angeles Los Angeles CA 90095 USA
- Current Address: Department of Chemistry Columbia University New York NY 10027 USA
| | - Julen Munarriz
- Department of Chemistry and Biochemistry University of California Los Angeles Los Angeles CA 90095 USA
| | - Michael E. Valentine
- Institute for Quantum Matter Department of Physics and Astronomy The Johns Hopkins University Baltimore MD 21218 USA
| | - Austin Granmoe
- Institute for Quantum Matter Department of Physics and Astronomy The Johns Hopkins University Baltimore MD 21218 USA
| | - Natalia Drichko
- Institute for Quantum Matter Department of Physics and Astronomy The Johns Hopkins University Baltimore MD 21218 USA
| | - Juan R. Chamorro
- Institute for Quantum Matter Department of Physics and Astronomy The Johns Hopkins University Baltimore MD 21218 USA
- Department of Chemistry The Johns Hopkins University Baltimore MD 21218 USA
| | | | - Tyrel M. McQueen
- Institute for Quantum Matter Department of Physics and Astronomy The Johns Hopkins University Baltimore MD 21218 USA
- Department of Chemistry The Johns Hopkins University Baltimore MD 21218 USA
- Department of Materials Science and Engineering The Johns Hopkins University Baltimore MD 21218 USA
| | - Anastassia N. Alexandrova
- Department of Chemistry and Biochemistry University of California Los Angeles Los Angeles CA 90095 USA
- California NanoSystems Institute Los Angeles CA 90095 USA
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7
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Robinson PJ, Munarriz J, Valentine ME, Granmoe A, Drichko N, Chamorro JR, Rosa PF, McQueen TM, Alexandrova AN. Dynamical Bonding Driving Mixed Valency in a Metal Boride. Angew Chem Int Ed Engl 2020; 59:10996-11002. [PMID: 32202032 DOI: 10.1002/anie.202000945] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Indexed: 11/08/2022]
Abstract
Samarium hexaboride is an anomaly, having many exotic and seemingly mutually incompatible properties. It was proposed to be a mixed-valent semiconductor, and later a topological Kondo insulator, and yet has a Fermi surface despite being an insulator. We propose a new and unified understanding of SmB6 centered on the hitherto unrecognized dynamical bonding effect: the coexistence of two Sm-B bonding modes within SmB6 , corresponding to different oxidation states of the Sm. The mixed valency arises in SmB6 from thermal population of these distinct minima enabled by motion of B. Our model simultaneously explains the thermal valence fluctuations, appearance of magnetic Fermi surface, excess entropy at low temperatures, pressure-induced phase transitions, and related features in Raman spectra and their unexpected dependence on temperature and boron isotope.
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Affiliation(s)
- Paul J Robinson
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, 90095, USA.,Current Address: Department of Chemistry, Columbia University, New York, NY, 10027, USA
| | - Julen Munarriz
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Michael E Valentine
- Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Austin Granmoe
- Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Natalia Drichko
- Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Juan R Chamorro
- Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | | | - Tyrel M McQueen
- Institute for Quantum Matter, Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Chemistry, The Johns Hopkins University, Baltimore, MD, 21218, USA.,Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Anastassia N Alexandrova
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, 90095, USA.,California NanoSystems Institute, Los Angeles, CA, 90095, USA
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8
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Qian T, Mutch J, Wu L, Went P, Jiang Q, Malinowski P, Yang J, Chu JH. Apparatus design for measuring of the strain dependence of the Seebeck coefficient of single crystals. Rev Sci Instrum 2020; 91:023902. [PMID: 32113413 DOI: 10.1063/1.5127530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 01/10/2020] [Indexed: 06/10/2023]
Abstract
We present the design and construction of an apparatus that measures the Seebeck coefficient of single crystals under in situ tunable strain at cryogenic temperatures. A home-built three piezostack apparatus applies uni-axial stress to a single crystalline sample and modulates anisotropic strain up to 0.7%. An alternating heater system and cernox sensor thermometry measure the Seebeck coefficient along the uniaxial stress direction. To demonstrate the efficacy of this apparatus, we applied uniaxial stress to detwin single crystals of BaFe2As2 in the orthorhombic phase. The obtained Seebeck coefficient anisotropy is in good agreement with previous measurements using a mechanical clamp.
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Affiliation(s)
- Tiema Qian
- Department of Physics, University of Washington, Seattle, Washington 98105, USA
| | - Joshua Mutch
- Department of Physics, University of Washington, Seattle, Washington 98105, USA
| | - Lihua Wu
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98105, USA
| | - Preston Went
- Department of Physics, University of Washington, Seattle, Washington 98105, USA
| | - Qianni Jiang
- Department of Physics, University of Washington, Seattle, Washington 98105, USA
| | - Paul Malinowski
- Department of Physics, University of Washington, Seattle, Washington 98105, USA
| | - Jihui Yang
- Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98105, USA
| | - Jiun-Haw Chu
- Department of Physics, University of Washington, Seattle, Washington 98105, USA
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9
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Barber ME, Steppke A, Mackenzie AP, Hicks CW. Piezoelectric-based uniaxial pressure cell with integrated force and displacement sensors. Rev Sci Instrum 2019; 90:023904. [PMID: 30831706 DOI: 10.1063/1.5075485] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/18/2019] [Indexed: 06/09/2023]
Abstract
We present a design for a piezoelectric-driven uniaxial stress cell suitable for use at ambient and cryogenic temperatures and that incorporates both a displacement and a force sensor. The cell has a diameter of 46 mm and a height of 13 mm. It can apply a zero-load displacement of up to ∼45 μm and a zero-displacement force of up to ∼245 N. With combined knowledge of the displacement and force applied to the sample, it can quickly be determined whether the sample and its mounts remain within their elastic limits. In tests on the oxide metal Sr2RuO4, we found that at room temperature serious plastic deformation of the sample onset at a uniaxial stress of ∼0.2 GPa, while at 5 K the sample deformation remained elastic up to almost 2 GPa. This result highlights the usefulness of in situ tuning, in which the force can be applied after cooling samples to cryogenic temperatures.
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Affiliation(s)
- Mark E Barber
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, Dresden 01187, Germany
| | - Alexander Steppke
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, Dresden 01187, Germany
| | - Andrew P Mackenzie
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, Dresden 01187, Germany
| | - Clifford W Hicks
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, Dresden 01187, Germany
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10
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Zhang YJ, Xia XB, Jiang WB, Wang YF, Liu JY, Yuan HQ, Lee H. Single crystal growth and anisotropic physical properties of Sm 4Co 3Ga 16. J Phys Condens Matter 2018; 30:345701. [PMID: 30010612 DOI: 10.1088/1361-648x/aad39c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We have synthesized high quality single crystals of Sm4Co3Ga16 with gallium flux and investigated its physical properties with electrical resistivity, magnetization and specific-heat measurements. Antiferromagnetic transition below 6.7 K has been detected. No superconducting transitions have been dectected down to 0.5 K from our single crystals. Based on our experimental result, Sm3+ state in Sm4Co3Ga16 is likely well localized, in which stable magnetic moment in its doubly degenerated ground state contributes to the magnetic order with little interference of Kondo type of interaction.
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Affiliation(s)
- Y J Zhang
- Center for Correlated Matter and Department of Physics, Zhejiang University, Hangzhou 310027, People's Republic of China
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11
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Liu T, Li Y, Gu L, Ding J, Chang H, Janantha PAP, Kalinikos B, Novosad V, Hoffmann A, Wu R, Chien CL, Wu M. Nontrivial Nature and Penetration Depth of Topological Surface States in SmB_{6} Thin Films. Phys Rev Lett 2018; 120:207206. [PMID: 29864320 DOI: 10.1103/physrevlett.120.207206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 06/08/2023]
Abstract
The nontrivial feature and penetration depth of the topological surface states (TSS) in SmB_{6} were studied via spin pumping. The experiments used SmB_{6} thin films grown on the bulk magnetic insulator Y_{3}Fe_{5}O_{12} (YIG). Upon the excitation of magnetization precession in the YIG, a spin current is generated in the SmB_{6} that produces, via spin-orbit coupling, a lateral electrical voltage in the film. This spin-pumping voltage signal becomes considerably stronger as the temperature decreases from 150 to 10 K, and such an enhancement most likely originates from the spin-momentum locking of the TSS and may thereby serve as evidence for the nontrivial nature of the TSS. The voltage data also show a unique film thickness dependence that suggests a TSS depth of ∼32 nm. The spin-pumping results are supported by transport measurements and analyses using a tight binding model.
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Affiliation(s)
- Tao Liu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Yufan Li
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Lei Gu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Junjia Ding
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Houchen Chang
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - P A Praveen Janantha
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Boris Kalinikos
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
- St. Petersburg Electrotechnical University, St. Petersburg 197376, Russia
| | - Valentyn Novosad
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - C L Chien
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Mingzhong Wu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
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12
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Abstract
In recent years, studying the Kondo insulator SmB6, a strongly correlated electron material that has been puzzling the community for decades, has again become an attractive topic due to the discovery of its unusual metallic surface state coexisting with the bulk insulating state. Many efforts have been made to understand the microphysics in SmB6, but some puzzles that have been hotly debated and argued have not been solved. In this article, based on the latest progress made in our high-pressure studies on SmB6 and the accumulating results reported by other groups, we propose a notion named the 'accompany-type valence fluctuation state', which possibly coexists with the bulk Kondo insulating ground state of SmB6. We expect that this notion could be taken as a common starting point for understanding in a unified way most of the low-temperature phenomena observed by different experimental investigations on SmB6, thus promoting the deciphering of the puzzles. We also expect that this notion could attract rigorous theoretical interpretation and further experimental investigation, or stimulate better thinking on the physics in SmB6.
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Affiliation(s)
- Qi Wu
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People's Republic of China
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13
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Kissikov T, Sarkar R, Bush BT, Lawson M, Canfield PC, Curro NJ. Nuclear magnetic resonance probe head design for precision strain control. Rev Sci Instrum 2017; 88:103902. [PMID: 29092471 DOI: 10.1063/1.5002631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We present the design and construction of an NMR probe to investigate single crystals under strain at cryogenic temperatures. The probe head incorporates a piezoelectric-based apparatus from Razorbill Instruments that enables both compressive and tensile strain tuning up to strain values on the order of 0.3% with a precision of 0.001%. 75As NMR in BaFe2As2 reveals large changes to the electric field gradient and indicates that the strain is homogeneous to within 16% over the volume of the NMR coil.
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Affiliation(s)
- T Kissikov
- Department of Physics, University of California, Davis, California 95616, USA
| | - R Sarkar
- Institute for Solid State Physics, TU Dresden, D-01069 Dresden, Germany
| | - B T Bush
- Department of Physics, University of California, Davis, California 95616, USA
| | - M Lawson
- Department of Physics, University of California, Davis, California 95616, USA
| | - P C Canfield
- Ames Laboratory U.S. DOE and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA
| | - N J Curro
- Department of Physics, University of California, Davis, California 95616, USA
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Sousanis A, Smet PF, Poelman D. Samarium Monosulfide (SmS): Reviewing Properties and Applications. Materials (Basel) 2017; 10:E953. [PMID: 28813006 DOI: 10.3390/ma10080953] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/31/2017] [Accepted: 08/10/2017] [Indexed: 11/17/2022]
Abstract
In this review, we give an overview of the properties and applications of samarium monosulfide, SmS, which has gained considerable interest as a switchable material. It shows a pressure-induced phase transition from the semiconducting to the metallic state by polishing, and it switches back to the semiconducting state by heating. The material also shows a magnetic transition, from the paramagnetic state to an antiferromagnetically ordered state. The switching behavior between the semiconducting and metallic states could be exploited in several applications, such as high density optical storage and memory materials, thermovoltaic devices, infrared sensors and more. We discuss the electronic, optical and magnetic properties of SmS, its switching behavior, as well as the thin film deposition techniques which have been used, such as e-beam evaporation and sputtering. Moreover, applications and possible ideas for future work on this material are presented. Our scope is to present the properties of SmS, which were mainly measured in bulk crystals, while at the same time we describe the possible deposition methods that will push the study of SmS to nanoscale dimensions, opening an intriguing range of applications for low-dimensional, pressure-induced semiconductor-metal transition compounds.
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Mackenzie AP, Hicks CW. Topological Kondo insulators: Negative pressure tuning. Nat Mater 2017; 16:702-703. [PMID: 28653693 DOI: 10.1038/nmat4925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Affiliation(s)
- Andrew P Mackenzie
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Clifford W Hicks
- Max Planck Institute for Chemical Physics of Solids, 01187 Dresden, Germany
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