Magnetically hidden state on the ground floor of the magnetic Devil's staircase

Abstract

We investigated the low-temperature and high-field thermodynamic and ultrasonic properties of SrCu2(BO3)2, which exhibits various plateaux in its magnetization curve above 27~T, called a magnetic Devil's staircase. The results of the present study confirm that magnetic crystallization, the first step of the staircase, occurs above 27~T as a 1st-order transition accompanied by a sharp singularity in heat capacity $C_p$ and a kink in the elastic constant. In addition, we observe a thermodynamic anomaly at lower fields around 26~T, which has not been previously detected by any magnetic probes. At low temperatures, this magnetically hidden state has a large entropy and does not exhibit Schottky-type gapped behavior, which suggests the existence of low-energy collective excitations. Based on our observations and theoretical predictions, we propose that magnetic quadrupoles form a spin-nematic state around 26~T as a hidden state on the ground floor of the magnetic Devil's staircase.

References in corpus (6)

• Incomplete devil's staircase in the magnetization curve of SrCu2(BO3)2
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• Field dependence of the quantum ground state in the Shastry-Sutherland system SrCu${}_2$(BO${}_3$)${}_2$
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• NMR evidence for the persistence of spin-superlattice above the 1/8 magnetization plateau in SrCu2(BO3)2
• High-resolution Calorimetry in Pulsed Magnetic Fields

Cited by in corpus (2)

• Unveiling new quantum phases in the Shastry-Sutherland compound SrCu2(BO3)2up to the saturation magnetic field
• Thermal first-order phase transitions, Ising critical points, and reentrance in the Ising-Heisenberg model on the diamond-decorated square lattice in a magnetic field