A quantum magnetic analogue to the critical point of water

Author(s):Show less -

Larrea Jimenez, J. ^{[1, 2]} ; Crone, S. P. G. ^{[3, 4]} ; Fogh, E. ^[2] ; Zayed, M. E. ^[5] ; Lortz, R. ^[6] ; Pomjakushina, E. ^[7] ; Conder, K. ^[7] ; Laeuchli, A. M. ^[8] ; Weber, L. ^[9] ; Wessel, S. ^[9] ; Honecker, A. ^[10] ; Normand, B. ^{[11, 2]} ; Rueegg, Ch. ^{[11, 2, 12, 13]} ; Corboz, P. ^{[3, 4]} ; Ronnow, H. M. ^[2] ; Mila, F. ^[2]

Affiliation:Show less -

^[1] Univ Sao Paulo, Inst Phys, Lab Quantum Matter Extreme Condit, Sao Paulo - Brazil

^[2] Ecole Polytech Fed Lausanne EPFL, Inst Phys, Lausanne - Switzerland

^[3] Univ Amsterdam, Inst Theoret Phys, Amsterdam - Netherlands

^[4] Univ Amsterdam, Delta Inst Theoret Phys, Amsterdam - Netherlands

^[5] Carnegie Mellon Univ Qatar, Dept Phys, Doha - Qatar

^[6] Hong Kong Univ Sci & Technol, Dept Phys, Kowloon, Hong Kong - Peoples R China

^[7] Paul Scherrer Inst, Lab Multiscale Mat Expt, Villigen - Switzerland

^[8] Univ Innsbruck, Inst Theoret Phys, Innsbruck - Austria

^[9] Rhein Westfal TH Aachen, Inst Theoret Festkorperphys, Aachen - Germany

^[10] CY Cergy Paris Univ, CNRS, UMR 8089, Lab Phys Theor & Modelisat, Cergy Pontoise - France

^[11] Paul Scherrer Inst, Villigen - Switzerland

^[12] Swiss Fed Inst Technol, Inst Quantum Elect, Hongg - Switzerland

^[13] Univ Geneva, Dept Quantum Matter Phys, Geneva - Switzerland

• Document type: Journal article
• Source: Nature; v. 592, n. 7854, p. 370+, APR 15 2021.
• Web of Science Citations: 3

Abstract

At the liquid-gas phase transition in water, the density has a discontinuity at atmospheric pressure; however, the line of these first-order transitions defined by increasing the applied pressure terminates at the critical point(1), a concept ubiquitous in statistical thermodynamics(2). In correlated quantum materials, it was predicted(3) and then confirmed experimentally(4,5) that a critical point terminates the line of Mott metal-insulator transitions, which are also first-order with a discontinuous charge carrier density. In quantum spin systems, continuous quantum phase transitions(6) have been controlled by pressure(7,8), applied magnetic field(9,10) and disorder(11), but discontinuous quantum phase transitions have received less attention. The geometrically frustrated quantum antiferromagnet SrCu2(BO3)(2) constitutes a near-exact realization of the paradigmatic Shastry-Sutherland model(12-14) and displays exotic phenomena including magnetization plateaus(15), low-lying bound-state excitations(16), anomalous thermodynamics(17) and discontinuous quantum phase transitions(18,19). Here we control both the pressure and the magnetic field applied to SrCu2(BO3)(2) to provide evidence of critical-point physics in a pure spin system. We use high-precision specific-heat measurements to demonstrate that, as in water, the pressure-temperature phase diagram has a first-order transition line that separates phases with different local magnetic energy densities, and that terminates at an Ising critical point. We provide a quantitative explanation of our data using recently developed finite-temperature tensor-network methods(17,20-22). These results further our understanding of first-order quantum phase transitions in quantum magnetism, with potential applications in materials where anisotropic spin interactions produce the topological properties(23,24) that are useful for spintronic applications. (AU)

• FAPESP's process: 18/08845-3 - An investigation into topological and exotic quantum states under extreme conditions (InvestInTopQuantEx)
• Grantee: Julio Antonio Larrea Jimenez
• Support Opportunities: Research Grants - Young Investigators Grants