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Stellino E, D'Alò B, Capitani F, Verseils M, Brubach JB, Roy P, Nucara A, Petrillo C, Postorino P. Far-Infrared Signatures for a Two-Step Pressure-Driven Metallization in Transition Metal Dichalcogenides. J Phys Chem Lett 2023; 14:2133-2140. [PMID: 36802587 DOI: 10.1021/acs.jpclett.3c00199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
We present a high-pressure investigation of the semiconductor-to-metal transition in MoS2 and WS2 carried out by synchrotron-based far-infrared spectroscopy, to reconcile the controversial estimates of the metallization pressure found in the literature and gain new insight into the mechanisms ruling this electronic transition. Two spectral descriptors are found indicative of the onset of metallicity and of the origin of the free carriers in the metallic state: the absorbance spectral weight, whose abrupt increase defines the metallization pressure threshold, and the asymmetric line shape of the E1u peak, whose pressure evolution, interpreted within the Fano model, suggests the electrons in the metallic state originate from n-type doping levels. Combining our results with those reported in the literature, we hypothesize a two-step mechanism is at work in the metallization process, in which the pressure-induced hybridization between doping and conduction band states drives an early metallic behavior, while the band gap closes at higher pressures.
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Affiliation(s)
- Elena Stellino
- University of Perugia, Department of Physics and Geology, via Alessandro Pascoli, 06123, Perugia, Italy
| | - Beatrice D'Alò
- Sapienza University of Rome, Department of Physics, P.le A. Moro 5, 00185, Rome, Italy
| | - Francesco Capitani
- Synchrotron SOLEIL, L'Orme des Merisiers - Départementale 128, 91190 Saint-Aubin, France
| | - Marine Verseils
- Synchrotron SOLEIL, L'Orme des Merisiers - Départementale 128, 91190 Saint-Aubin, France
| | - Jean-Blaise Brubach
- Synchrotron SOLEIL, L'Orme des Merisiers - Départementale 128, 91190 Saint-Aubin, France
| | - Pascale Roy
- Synchrotron SOLEIL, L'Orme des Merisiers - Départementale 128, 91190 Saint-Aubin, France
| | - Alessandro Nucara
- Sapienza University of Rome, Department of Physics, P.le A. Moro 5, 00185, Rome, Italy
| | - Caterina Petrillo
- University of Perugia, Department of Physics and Geology, via Alessandro Pascoli, 06123, Perugia, Italy
| | - Paolo Postorino
- Sapienza University of Rome, Department of Physics, P.le A. Moro 5, 00185, Rome, Italy
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Liu C, Zhang B, Yu X, Wu X, Chen P, Yang P, Yu X, Ding J, Chen J, Chow GM. Magnetoelectric Coupling Induced Orbital Reconstruction and Ferromagnetic Insulating State in PbZr 0.52Ti 0.48O 3/La 0.67Sr 0.33MnO 3 Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2020; 12:35588-35597. [PMID: 32614572 DOI: 10.1021/acsami.0c07319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Novel phenomena at the ferromagnetic/ferroelectric interface have generated much interest. Here, a ferromagnetic insulating state with the Curie temperature about 268-286 K in PbZr0.52Ti0.48O3/La0.67Sr0.33MnO3 heterostructures is induced and modulated by varying the PbZr0.52Ti0.48O3 thickness. An abnormally enlarged c/a ratio in La0.67Sr0.33MnO3 by strain-based coupling effect leads to d3z2-r2 orbital preferable occupancy. This orbital reconstruction modulates effective electron transfer and finally leads to a ferromagnetic insulating state. Valence change induced by charge-based coupling effect could be partially responsible for change in the Curie temperature in the strongly correlated electron system of La1-xSrxMnO3. This work provides a deeper understanding of strain effects near the ferromagnetic/ferroelectric interface, especially in a PbZr1-yTiyO3/La1-xSrxMnO3 heterostructure system.
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Affiliation(s)
- Chao Liu
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
| | - Bangmin Zhang
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
- School of Physics, Sun Yat-Sen University, Guangzhou, Guangdong 510275, China
| | - Xiaoqian Yu
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
| | - Xiaohan Wu
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
| | - Pingfan Chen
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
| | - Ping Yang
- Singapore Synchrotron Light Source, National University of Singapore, 117603 Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, 117603 Singapore
| | - Jun Ding
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
| | - Jingsheng Chen
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
| | - Gan Moog Chow
- Department of Materials Science & Engineering, National University of Singapore, 117575 Singapore
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Abstract
The Mott insulator in correlated electron systems arises from classical Coulomb repulsion between carriers to provide a powerful force for electron localization. Turning such an insulator into a metal, the so-called Mott transition, is commonly achieved by "bandwidth" control or "band filling." However, both mechanisms deviate from the original concept of Mott, which attributes such a transition to the screening of Coulomb potential and associated lattice contraction. Here, we report a pressure-induced isostructural Mott transition in cubic perovskite PbCrO3. At the transition pressure of ∼3 GPa, PbCrO3 exhibits significant collapse in both lattice volume and Coulomb potential. Concurrent with the collapse, it transforms from a hybrid multiferroic insulator to a metal. For the first time to our knowledge, these findings validate the scenario conceived by Mott. Close to the Mott criticality at ∼300 K, fluctuations of the lattice and charge give rise to elastic anomalies and Laudau critical behaviors resembling the classic liquid-gas transition. The anomalously large lattice volume and Coulomb potential in the low-pressure insulating phase are largely associated with the ferroelectric distortion, which is substantially suppressed at high pressures, leading to the first-order phase transition without symmetry breaking.
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Marini C, Joseph B, Caramazza S, Capitani F, Bendele M, Mitrano M, Chermisi D, Mangialardo S, Pal B, Goyal M, Iadecola A, Mathon O, Pascarelli S, Sarma DD, Postorino P. Local disorder investigation in NiS(2-x)Se(x) using Raman and Ni K-edge x-ray absorption spectroscopies. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:452201. [PMID: 25320052 DOI: 10.1088/0953-8984/26/45/452201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on Raman and Ni K-edge x-ray absorption investigations of a NiS(2-x)Se(x) (with x = 0.00, 0.50/0.55, 0.60, and 1.20) pyrite family. The Ni K-edge absorption edge shows a systematic shift going from an insulating phase (x = 0.00 and 0.50) to a metallic phase (x = 0.60 and 1.20). The near-edge absorption features show a clear evolution with Se doping. The extended x-ray absorption fine structure data reveal the evolution of the local structure with Se doping which mainly governs the local disorder. We also describe the decomposition of the NiS(2-x)Se(x) Raman spectra and investigate the weights of various phonon modes using Gaussian and Lorentzian profiles. The effectiveness of the fitting models in describing the data is evaluated by means of Bayes factor estimation. The Raman analysis clearly demonstrates the disorder effects due to Se alloying in describing the phonon spectra of NiS(2-x)Se(x) pyrites.
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Affiliation(s)
- C Marini
- CELLS-ALBA, Carretera B.P. 1413, Cerdanyola del Vallès, 08290, Barcelona, Spain. ESRF-The European Synchrotron, 71 avenue des Martyrs, 38000 Grenoble, France
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Markovich V, Wisniewski A, Szymczak H. Magnetic Properties of Perovskite Manganites and Their Modifications. HANDBOOK OF MAGNETIC MATERIALS 2014. [DOI: 10.1016/b978-0-444-63291-3.00001-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
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Baldini M, Capogna L, Capone M, Arcangeletti E, Petrillo C, Goncharenko I, Postorino P. Pressure induced magnetic phase separation in La0.75Ca0.25MnO3 manganite. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:045601. [PMID: 22214651 DOI: 10.1088/0953-8984/24/4/045601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The pressure dependence of the Curie temperature T(C)(P) in La(0.75)Ca(0.25)MnO(3) was determined by neutron diffraction up to 8 GPa, and compared with the metallization temperature T(IM)(P) (Postorino et al 2003 Phys. Rev. Lett. 91 175501). The behavior of the two temperatures appears similar over the whole pressure range, suggesting a key role of magnetic double-exchange also in the pressure regime where the superexchange interaction is dominant. The coexistence of antiferromagnetic and ferromagnetic peaks at high pressure and low temperature indicates a phase separated regime which is well reproduced with a dynamical mean-field calculation for a simplified model. A new P-T phase diagram has been proposed on the basis of the whole set of experimental data.
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Affiliation(s)
- M Baldini
- Dipartimento di Fisica, Università Sapienza, Roma, Italy.
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Hu T, Cui X, Gao Y, Han Y, Liu C, Liu B, Liu H, Ma Y, Gao C. In situ Hall effect measurement on diamond anvil cell under high pressure. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2010; 81:115101. [PMID: 21133495 DOI: 10.1063/1.3501384] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A method for in situ Hall effect measurement under high pressure was developed on a diamond anvil cell. The electrode was accurately integrated on one diamond anvil with regular shape. A uniform and strong magnetic field was introduced into the sample zone. The voltage errors brought by some negative effects during the measurement were well eliminated. The correction factor of the Hall coefficient, brought by the nonpoint contact between the electrode and the sample, was 4.51%. The measurement error of the magnetic field did not exceed 1%. The carrier character of ZnTe powders was studied up to 23 GPa. The evolution of conductivity with pressure was explained based on the variation of the carrier behavior.
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Affiliation(s)
- Tingjing Hu
- State Key Laboratory of Superhard Materials, Institute of Atomic and Molecular Physics, College of Physics, Jilin University, Changchun 130012, People's Republic of China
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Ding Y, Haskel D, Tseng YC, Kaneshita E, van Veenendaal M, Mitchell JF, Sinogeikin SV, Prakapenka V, Mao HK. Pressure-induced magnetic transition in manganite (La0.75Ca0.25MnO3). PHYSICAL REVIEW LETTERS 2009; 102:237201. [PMID: 19658965 DOI: 10.1103/physrevlett.102.237201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Revised: 01/29/2009] [Indexed: 05/28/2023]
Abstract
Low temperature Mn K-edge x-ray magnetic circular dichroism and x-ray diffraction measurements were carried out to investigate the stability of the ferromagnetic ground state in manganite La0.75Ca0.25MnO3 under nearly uniform compression using diamond anvil cells. The magnetic dichroism signal gradually decreases with pressure and disappears at 23 GPa, and meanwhile a uniaxial compression of MnO6 octahedra along the b axis is observed to continuously increase with pressure and become anomalously large at 23.5 GPa. These changes are attributed to a ferromagnetic-antiferromagnetic transition that is associated with orbital ordering at high pressure.
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Affiliation(s)
- Yang Ding
- HPSynC, Carnegie Institution of Washington, Argonne, Illinois 60439, USA.
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Shenoy VB, Rao CNR. Electronic phase separation and other novel phenomena and properties exhibited by mixed-valent rare-earth manganites and related materials. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2008; 366:63-82. [PMID: 17827125 DOI: 10.1098/rsta.2007.2140] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Transition metal oxides, such as the mixed-valent rare-earth manganites Ln(1-x)AxMnO3 (Ln, rare-earth ion, and A, alkaline-earth ion), show a variety of electronic orders with spatially correlated charge, spin and orbital arrangements, which in turn give rise to many fascinating phenomena and properties. These materials are also electronically inhomogeneous, i.e. they contain disjoint spatial regions with different electronic orders. Not only do we observe signatures of such electronic phase separation in a variety of properties, but we can also observe the different 'phases' visually through different types of imaging. We discuss various experiments pertaining to electronic orders and electronic inhomogeneities in the manganites and present a discussion of theoretical approaches to their understanding. It is noteworthy that the mixed-valent rare-earth cobaltates of the type Ln(1-x)AxCoO3 also exhibit electronic inhomogeneities just as the manganites.
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Affiliation(s)
- Vijay B Shenoy
- Centre for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560 012, India
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Shenoy VB, Sarma DD, Rao CNR. Electronic Phase Separation in Correlated Oxides: The Phenomenon, Its Present Status and Future Prospects. Chemphyschem 2006; 7:2053-9. [PMID: 16929554 DOI: 10.1002/cphc.200600188] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Many transition metal oxide materials of high chemical purity are not necessarily monophasic. Thus, single crystals of chemically pure rare earth manganites and cobaltates of the general formula Ln(1-x)A(x)MO(3) (Ln=rare earth metal, A=alkaline earth metal, M=Mn, Co) exhibit the phenomenon of electronic phase separation wherein "phases" of different electronic and magnetic properties coexist. Such phase separation, the length scale of which can vary anywhere between a few nanometers to microns, gives distinct signatures in X-ray and neutron diffraction patterns, electrical and magnetic properties, as well as in NMR and other spectroscopies. While the probe one employs to investigate electronic phase separation depends on the length scale, it is noteworthy that direct imaging of the inhomogeneities has been accomplished. Some understanding of this phenomenon has been possible on the basis of some of the theoretical models, but we are far from unraveling the varied aspects of this new phenomenon. Herein, we present the highlights of experimental techniques and theoretical approaches, and comment on the future outlook for this fascinating phenomenon.
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Affiliation(s)
- Vijay B Shenoy
- Materials Research Centre and Centre for Condensed Matter Theory Indian Institute of Science, Bangalore, 560 012, India
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Sacchetti A, Guidi MC, Arcangeletti E, Nucara A, Calvani P, Piccinini M, Marcelli A, Postorino P. Far-infrared absorption of La1-xCaxMnO3-y at high pressure. PHYSICAL REVIEW LETTERS 2006; 96:035503. [PMID: 16486724 DOI: 10.1103/physrevlett.96.035503] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Indexed: 05/06/2023]
Abstract
The first far-infrared absorption spectra of manganite samples at pressures P up to 10 GPa were obtained on La1-xCaxMnO3-y by use of synchrotron radiation. For x=0.25 and 0.20 (y=0), P promotes partial metallization at room temperature through a strong reduction of the insulating gap. An x=0.20 sample with y=0.08 does not show any charge delocalization effect up to 10 GPa. An Urbach-like model of disordered Jahn-Teller wells is shown to well fit the far-infrared band edge and allows one to obtain a reliable pressure dependence of the energy gap.
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Affiliation(s)
- A Sacchetti
- Coherentia CNR-INFM and Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Roma, Italy
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