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Xiang J, Zhang C, Gao Y, Schmidt W, Schmalzl K, Wang CW, Li B, Xi N, Liu XY, Jin H, Li G, Shen J, Chen Z, Qi Y, Wan Y, Jin W, Li W, Sun P, Su G. Giant magnetocaloric effect in spin supersolid candidate Na 2BaCo(PO 4) 2. Nature 2024; 625:270-275. [PMID: 38200301 DOI: 10.1038/s41586-023-06885-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/21/2023] [Indexed: 01/12/2024]
Abstract
Supersolid, an exotic quantum state of matter that consists of particles forming an incompressible solid structure while simultaneously showing superfluidity of zero viscosity1, is one of the long-standing pursuits in fundamental research2,3. Although the initial report of 4He supersolid turned out to be an artefact4, this intriguing quantum matter has inspired enthusiastic investigations into ultracold quantum gases5-8. Nevertheless, the realization of supersolidity in condensed matter remains elusive. Here we find evidence for a quantum magnetic analogue of supersolid-the spin supersolid-in the recently synthesized triangular-lattice antiferromagnet Na2BaCo(PO4)2 (ref. 9). Notably, a giant magnetocaloric effect related to the spin supersolidity is observed in the demagnetization cooling process, manifesting itself as two prominent valley-like regimes, with the lowest temperature attaining below 100 mK. Not only is there an experimentally determined series of critical fields but the demagnetization cooling profile also shows excellent agreement with the theoretical simulations with an easy-axis Heisenberg model. Neutron diffractions also successfully locate the proposed spin supersolid phases by revealing the coexistence of three-sublattice spin solid order and interlayer incommensurability indicative of the spin superfluidity. Thus, our results reveal a strong entropic effect of the spin supersolid phase in a frustrated quantum magnet and open up a viable and promising avenue for applications in sub-kelvin refrigeration, especially in the context of persistent concerns about helium shortages10,11.
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Affiliation(s)
- Junsen Xiang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Chuandi Zhang
- School of Physics, Beihang University, Beijing, China
| | - Yuan Gao
- School of Physics, Beihang University, Beijing, China
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China
| | - Wolfgang Schmidt
- Jülich Centre for Neutron Science at Institut Laue-Langevin (ILL), Forschungszentrum Jülich GmbH, Grenoble Cedex 9, France
| | - Karin Schmalzl
- Jülich Centre for Neutron Science at Institut Laue-Langevin (ILL), Forschungszentrum Jülich GmbH, Grenoble Cedex 9, France
| | - Chin-Wei Wang
- Australian Nuclear Science and Technology Organisation, Lucas Heights, New South Wales, Australia
| | - Bo Li
- School of Physics, Beihang University, Beijing, China
| | - Ning Xi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China
| | - Xin-Yang Liu
- School of Physics, Beihang University, Beijing, China
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China
| | - Hai Jin
- Department of Astronomy, Tsinghua University, Beijing, China
| | - Gang Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Jun Shen
- Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, China
| | - Ziyu Chen
- School of Physics, Beihang University, Beijing, China
| | - Yang Qi
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China
| | - Yuan Wan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Wentao Jin
- School of Physics, Beihang University, Beijing, China.
| | - Wei Li
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China.
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijng, China.
- Peng Huanwu Collaborative Center for Research and Education, Beihang University, Beijing, China.
| | - Peijie Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.
| | - Gang Su
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijng, China.
- Kavli Institute for Theoretical Sciences, and School of Physical Sciences, University of Chinese Academy of Sciences, Beijng, China.
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Sichelschmidt J, Gruner T, Das D, Hossain Z. Electron spin resonance of the itinerant ferromagnets LaCrGe 3, CeCrGe 3and PrCrGe 3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:495605. [PMID: 34534978 DOI: 10.1088/1361-648x/ac27d7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 09/17/2021] [Indexed: 06/13/2023]
Abstract
We report electron spin resonance of the itinerant ferromagnets LaCrGe3, CeCrGe3, and PrCrGe3. These compounds show well defined and very similar spectra of itinerant Cr 3dspins in the paramagnetic temperature region. Upon cooling and crossing the Cr-ferromagnetic ordering (below around 90 K) strong spectral structures start to dominate the resonance spectra in a quite different manner in the three compounds. In the Ce- and Pr-compounds the resonance is only visible in the paramagnetic region whereas in the La-compound the resonance can be followed far below the ferromagnetic ordering temperature. This behavior will be discussed in terms of the specific interplay between the 4fand 3dmagnetism which appears quite remarkable since CeCrGe3displays heavy fermion behavior even in the magnetically ordered state.
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Affiliation(s)
- Jörg Sichelschmidt
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Thomas Gruner
- Max Planck Institute for Chemical Physics of Solids, D-01187 Dresden, Germany
| | - Debarchan Das
- Department of Physics, Indian Institute of Technology, Kanpur 208016, India
| | - Zakir Hossain
- Department of Physics, Indian Institute of Technology, Kanpur 208016, India
- Institute of Low Temperature and Structure Research, Okólna 2, 50-422 Wroclaw, Poland
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Kundu M, Pakhira S, Choudhary R, Paudyal D, Lakshminarasimhan N, Avdeev M, Cottrell S, Adroja D, Ranganathan R, Mazumdar C. Complex magnetic properties associated with competing local and itinerant magnetism in [Formula: see text]. Sci Rep 2021; 11:13245. [PMID: 34168172 PMCID: PMC8225917 DOI: 10.1038/s41598-021-90751-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Accepted: 05/12/2021] [Indexed: 12/03/2022] Open
Abstract
Ternary intermetallic compound [Formula: see text] has been synthesized in single phase and characterized by x-ray diffraction, scanning electron microscopy with energy dispersive x-ray spectroscopy (SEM-EDX) analysis, magnetization, heat capacity, neutron diffraction and muon spin rotation/relaxation ([Formula: see text]SR) measurements. The polycrystalline compound was synthesized in single phase by introducing necessary vacancies in Co/Si sites. Magnetic, heat capacity, and zero-field neutron diffraction studies reveal that the system undergoes magnetic transition below [Formula: see text]4 K. Neutron diffraction measurement further reveals that the magnetic ordering is antiferromagnetic in nature with an weak ordered moment. The high temperature magnetic phase has been attributed to glassy in nature consisting of ferromagnetic clusters of itinerant (3d) Co moments as evident by the development of internal field in zero-field [Formula: see text]SR below 50 K. The density-functional theory (DFT) calculations suggest that the low temperature magnetic transition is associated with antiferromagnetic coupling between Pr 4f and Co 3d spins. Pr moments show spin fluctuation along with unconventional orbital moment quenching due to crystal field. The evolution of the symmetry and the crystalline electric field environment of Pr-ions are also studied and compared theoretically between the elemental Pr and when it is coupled with other elements such as Co. The localized moment of Pr 4f and itinerant moment of Co 3d compete with each other below [Formula: see text]20 K resulting in an unusual temperature dependence of magnetic coercivity in the system.
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Affiliation(s)
- Mily Kundu
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700064 India
| | - Santanu Pakhira
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700064 India
- Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011 USA
| | - Renu Choudhary
- Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011 USA
| | - Durga Paudyal
- Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011 USA
- Electrical and Computer Engineering Department, Iowa State University, Ames, Iowa 50011 USA
| | - N. Lakshminarasimhan
- Electro-organic and Materials Electrochemistry Division, CSIR-Central Electrochemical Research Institute, Karaikudi, 630 003 India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201 002 India
| | - Maxim Avdeev
- Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234 Australia
- School of Chemistry, The University of Sydney, Sydney, NSW 2006 Australia
| | - Stephen Cottrell
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX UK
| | - Devashibhai Adroja
- ISIS Facility, STFC, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX UK
- Highly Correlated Matter Research Group, Physics Department, University of Johannesburg, PO Box 524, Auckland Park, 2006 South Africa
| | - R. Ranganathan
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700064 India
| | - Chandan Mazumdar
- Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, 700064 India
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Thermodynamics of General Heisenberg Spin Tetramers Composed of Coupled Quantum Dimers. MAGNETOCHEMISTRY 2021. [DOI: 10.3390/magnetochemistry7020029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Advances in quantum computing technology have been made in recent years due to the evolution of spin clusters. Recent studies have tended towards spin cluster subgeometries to understand more complex structures better. These molecular magnets provide a multitude of phenomena via exchange interactions that allow for advancements in spintronics and other magnetic system applications due to the possibility of increasing speed, data storage, memory, and stability of quantum computing systems. Using the Heisenberg spin–spin exchange Hamiltonian and exact diagonalization, we examine the evolution of quantum energy levels and thermodynamic properties for various spin configurations and exchange interactions. The XXYY quantum spin tetramer considered in this study consists of two coupled dimers with exchange interactions α1J and α1′J and a dimer–dimer exchange interaction α2J. By varying spin values and interaction strengths, we determine the exact energy eigenstates that are used to determine closed-form analytic solutions for the heat capacity and magnetic susceptibility of the system and further analyze the evolution of the properties of the system based on the parameter values chosen. Furthermore, this study shows that the Schottky anomaly shifts towards zero as the ground-state of the system approaches a quantum phase transition between spin states. Additionally, we investigate the development of phase transitions produced by the convergence of the Schottky anomaly with both variable exchange interactions and external magnetic field.
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