1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Luo F, Zhu C, Wang J, He X, Yang Z, Ke S, Zhang Y, Liu H, Sun Z. Magnetically Enhanced Thermoelectric Performance of Ti 0.75NiSb+ x mol % Fe ( x = 0-5) Nanocomposites. ACS APPLIED MATERIALS & INTERFACES 2022; 14:45503-45515. [PMID: 36184800 DOI: 10.1021/acsami.2c14450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Ti0.75NiSb is a half-Heusler compound with low lattice thermal conductivity due to a large number of cation vacancies. However, the higher carrier concentration limits the improvement of its thermoelectric performance. In this paper, magnetic Fe nanoparticles with a size of 30 nm are composited into Ti0.75NiSb in the form of the second phase. The charge transfer between Fe nanoparticles and Ti0.75NiSb leads to a decrease in carrier concentration. The strong interaction between the magnetic moment and carriers enhances the electron scattering, so that the scattering factor increases and the mobility decreases. The combined effect results in an increase of about 10% in the Seebeck coefficient and a decrease by about 14% in the electronic thermal conductivity at 873 K for the composite Ti0.75NiSb+2 mol % Fe. Meanwhile, the magnetic Fe nanoparticles provide additional scattering centers, leading to a decrease in lattice thermal conductivity. As a result, a zT value of 0.4 at 873 K is achieved for the composite Ti0.75NiSb+2 mol % Fe, which is 21% higher than that of Ti0.75NiSb. This work demonstrates that the compositing magnetic nanoparticles Fe can enhance the thermoelectric performance of Ti0.75NiSb.
Collapse
Affiliation(s)
- Feng Luo
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan430070, People's Republic of China
| | - Can Zhu
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan430070, People's Republic of China
| | - Jian Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan430070, People's Republic of China
| | - Xiong He
- Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan430074, People's Republic of China
| | - Zhen Yang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan430070, People's Republic of China
| | - Shaoqiu Ke
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan430070, People's Republic of China
| | - Yan Zhang
- Material Science and Engineering School, Taiyuan University of Science and Technology, Taiyuan030024, People's Republic of China
| | - Hongxia Liu
- Material Science and Engineering School, Taiyuan University of Science and Technology, Taiyuan030024, People's Republic of China
| | - Zhigang Sun
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan430070, People's Republic of China
- Material Science and Engineering School, Taiyuan University of Science and Technology, Taiyuan030024, People's Republic of China
| |
Collapse
|
3
|
Abstract
One of the main developments in unconventional superconductivity in the past two decades has been the discovery that most unconventional superconductors form phase diagrams that also contain other strongly correlated states. Many systems of interest are therefore close to more than one instability, and tuning between the resultant ordered phases is the subject of intense research1. In recent years, uniaxial pressure applied using piezoelectric-based devices has been shown to be a particularly versatile new method of tuning2,3, leading to experiments that have advanced our understanding of the fascinating unconventional superconductor Sr2RuO4 (refs. 4–9). Here we map out its phase diagram using high-precision measurements of the elastocaloric effect in what we believe to be the first such study including both the normal and the superconducting states. We observe a strong entropy quench on entering the superconducting state, in excellent agreement with a model calculation for pairing at the Van Hove point, and obtain a quantitative estimate of the entropy change associated with entry to a magnetic state that is observed in proximity to the superconductivity. The phase diagram is intriguing both for its similarity to those seen in other families of unconventional superconductors and for extra features unique, so far, to Sr2RuO4. The phase diagram of the unconventional superconductor Sr2RuO4 in both normal and superconducting states is mapped out using high-precision measurements of the elastocaloric effect, showing similarities to other unconventional superconductors as well as unique features.
Collapse
|
4
|
Anisotropy-driven quantum criticality in an intermediate valence system. Nat Commun 2022; 13:2141. [PMID: 35440657 PMCID: PMC9019086 DOI: 10.1038/s41467-022-29757-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 03/29/2022] [Indexed: 11/08/2022] Open
Abstract
Intermetallic compounds containing f-electron elements have been prototypical materials for investigating strong electron correlations and quantum criticality (QC). Their heavy fermion ground state evoked by the magnetic f-electrons is susceptible to the onset of quantum phases, such as magnetism or superconductivity, due to the enhanced effective mass (m*) and a corresponding decrease of the Fermi temperature. However, the presence of f-electron valence fluctuations to a non-magnetic state is regarded an anathema to QC, as it usually generates a paramagnetic Fermi-liquid state with quasiparticles of moderate m*. Such systems are typically isotropic, with a characteristic energy scale T0 of the order of hundreds of kelvins that require large magnetic fields or pressures to promote a valence or magnetic instability. Here we show the discovery of a quantum critical behaviour and a Lifshitz transition under low magnetic field in an intermediate valence compound α-YbAlB4. The QC origin is attributed to the anisotropic hybridization between the conduction and localized f-electrons. These findings suggest a new route to bypass the large valence energy scale in developing the QC. The nature of quantum criticality in intermetallic f-electron compounds exhibiting valence fluctuations is not well understood. Here, using a combination of experimental techniques, the authors attribute quantum criticality in YbAlB4 to the anisotropic hybridization between the conduction and f-electrons.
Collapse
|
5
|
Yu S, Gao Y, Chen BB, Li W. Learning the Effective Spin Hamiltonian of a Quantum Magnet. CHINESE PHYSICS LETTERS 2021; 38:097502. [DOI: 10.1088/0256-307x/38/9/097502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
To understand the intriguing many-body states and effects in the correlated quantum materials, inference of the microscopic effective Hamiltonian from experiments constitutes an important yet very challenging inverse problem. Here we propose an unbiased and efficient approach learning the effective Hamiltonian through the many-body analysis of the measured thermal data. Our approach combines the strategies including the automatic gradient and Bayesian optimization with the thermodynamics many-body solvers including the exact diagonalization and the tensor renormalization group methods. We showcase the accuracy and powerfulness of the Hamiltonian learning by applying it firstly to the thermal data generated from a given spin model, and then to realistic experimental data measured in the spin-chain compound copper nitrate and triangular-lattice magnet TmMgGaO4. The present automatic approach constitutes a unified framework of many-body thermal data analysis in the studies of quantum magnets and strongly correlated materials in general.
Collapse
|
6
|
Quasi-1D XY antiferromagnet Sr 2Ni(SeO 3) 2Cl 2 at Sakai-Takahashi phase diagram. Sci Rep 2021; 11:15002. [PMID: 34294799 PMCID: PMC8298402 DOI: 10.1038/s41598-021-94390-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 06/29/2021] [Indexed: 11/12/2022] Open
Abstract
Uniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr2Ni(SeO3)2Cl2, is a spin-1 chain system which passes through a correlations regime at Tmax ~ 12 K to long-range order at TN = 6 K. Under external magnetic field it experiences the sequence of spin-flop at Bc1 = 9.0 T and spin-flip transitions Bc2 = 23.7 T prior to full saturation at Bsat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram.
Collapse
|
7
|
Fuhrman WT, Sidorenko A, Hänel J, Winkler H, Prokofiev A, Rodriguez-Rivera JA, Qiu Y, Blaha P, Si Q, Broholm CL, Paschen S. Pristine quantum criticality in a Kondo semimetal. SCIENCE ADVANCES 2021; 7:eabf9134. [PMID: 34138738 PMCID: PMC8133744 DOI: 10.1126/sciadv.abf9134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
The observation of quantum criticality in diverse classes of strongly correlated electron systems has been instrumental in establishing ordering principles, discovering new phases, and identifying the relevant degrees of freedom and interactions. At focus so far have been insulators and metals. Semimetals, which are of great current interest as candidate phases with nontrivial topology, are much less explored in experiments. Here, we study the Kondo semimetal CeRu4Sn6 by magnetic susceptibility, specific heat, and inelastic neutron scattering experiments. The power-law divergence of the magnetic Grünesien ratio reveals that, unexpectedly, this compound is quantum critical without tuning. The dynamical energy over temperature scaling in the neutron response throughout the Brillouin zone and the temperature dependence of the static uniform susceptibility, indicate that temperature is the only energy scale in the criticality. Such behavior, which has been associated with Kondo destruction quantum criticality in metallic systems, could be generic in the semimetal setting.
Collapse
Affiliation(s)
- Wesley T Fuhrman
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Andrey Sidorenko
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Jonathan Hänel
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Hannes Winkler
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Andrey Prokofiev
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria
| | - Jose A Rodriguez-Rivera
- Department of Materials Sciences, University of Maryland, College Park, MD 20742, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Yiming Qiu
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Peter Blaha
- Institute of Materials Chemistry, Vienna University of Technology, 1040 Vienna, Austria
| | - Qimiao Si
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| | - Collin L Broholm
- Institute for Quantum Matter and Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
- Department of Materials Science and Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
| | - Silke Paschen
- Institute of Solid State Physics, Vienna University of Technology, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria.
- Department of Physics and Astronomy, Rice Center for Quantum Materials, Rice University, Houston, TX 77005, USA
| |
Collapse
|
8
|
Zhang L. Universal Thermodynamic Signature of Self-Dual Quantum Critical Points. PHYSICAL REVIEW LETTERS 2019; 123:230601. [PMID: 31868494 DOI: 10.1103/physrevlett.123.230601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 08/25/2019] [Indexed: 06/10/2023]
Abstract
Self-duality is an algebraic structure of certain critical theories, which is not encoded in the scaling dimensions and critical exponents. In this work, a universal thermodynamic signature of self-dual quantum critical points (QCPs) is proposed. It is shown that the Grüneisen ratio at a self-dual QCP remains finite as T→0, which is in sharp contrast to its universal divergence at a generic QCP without self-duality, Γ(T,g_{c})∼T^{-1/zν}. This conclusion is drawn based on the hyperscaling theory near the QCP, and has far-reaching implications for experiments and numerical simulations.
Collapse
Affiliation(s)
- Long Zhang
- Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China and Physical Science Laboratory, Huairou National Comprehensive Science Center, Beijing 101400, China
| |
Collapse
|
9
|
Chakraborty T, Mitra C. Magnetocaloric effect as a signature of quantum level-crossing for a spin-gapped system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:475802. [PMID: 31390596 DOI: 10.1088/1361-648x/ab3962] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Recent research dealing with magnetocaloric effect (MCE) study of antiferromagnetic (AFM) low dimensional spin systems have revealed a number of fascinating ground-state crossover characteristics upon application of external magnetic field. Herein, through MCE investigation we have explored field-induced quantum level-crossing characteristics of one such spin system: [Formula: see text] (NCP), an AFM spin 1/2 dimer. Experimental magnetization and specific heat data are presented and the data have been employed to evaluate entropy, magnetic energy and magnetocaloric properties. We witness a sign change in magnetic Grüneisen parameter across the level-crossing field B C . An adiabatic cooling is observed at low temperature by tracing the isentropic curves in temperature-magnetic field plane. Energy-level crossover characteristics in NCP interpreted through MCE analysis are well consistent with the observations made from magnetization and specific heat data.
Collapse
Affiliation(s)
- Tanmoy Chakraborty
- Indian Institute of Science Education and Research (IISER) Kolkata, Nadia-741246, West Bengal, India. Institute for Materials Research (IMO), Hasselt University, Wetenschapspark 1, B-3590 Diepenbeek, Belgium
| | | |
Collapse
|
10
|
Xiang JS, Chen C, Li W, Sheng XL, Su N, Cheng ZH, Chen Q, Chen ZY. Criticality-Enhanced Magnetocaloric Effect in Quantum Spin Chain Material Copper Nitrate. Sci Rep 2017; 7:44643. [PMID: 28294147 PMCID: PMC5353727 DOI: 10.1038/srep44643] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 02/13/2017] [Indexed: 11/08/2022] Open
Abstract
In this work, a systematic study of Cu(NO3)2·2.5 H2O (copper nitrate hemipentahydrate, CN), an alternating Heisenberg antiferromagnetic chain model material, is performed with multi-technique approach including thermal tensor network (TTN) simulations, first-principles calculations, as well as magnetization measurements. Employing a cutting-edge TTN method developed in the present work, we verify the couplings J = 5.13 K, α = 0.23(1) and Landé factors g∥= 2.31, g⊥ = 2.14 in CN, with which the magnetothermal properties have been fitted strikingly well. Based on first-principles calculations, we reveal explicitly the spin chain scenario in CN by displaying the calculated electron density distributions, from which the distinct superexchange paths are visualized. On top of that, we investigated the magnetocaloric effect (MCE) in CN by calculating its isentropes and magnetic Grüneisen parameter. Prominent quantum criticality-enhanced MCE was uncovered near both critical fields of intermediate strengths as 2.87 and 4.08 T, respectively. We propose that CN is potentially a very promising quantum critical coolant.
Collapse
Affiliation(s)
- Jun-Sen Xiang
- Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China
| | - Cong Chen
- Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China
| | - Wei Li
- Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China
- International Research Institute of Multidisciplinary Science, Beihang University, Beijing 100191, China
| | - Xian-Lei Sheng
- Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716-2570, USA
| | - Na Su
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhao-Hua Cheng
- State Key Laboratory of Magnetism and Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Qiang Chen
- Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China
| | - Zi-Yu Chen
- Department of Physics, Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191, China
| |
Collapse
|