Field-induced Bose-Einstein Condensation of triplons up to 8 K in Sr3Cr2O8

TL;DR

This study reports the first growth of single crystals of Sr3Cr2O8 and demonstrates field-induced Bose-Einstein condensation of triplons up to 8 K, revealing a new quantum magnet with accessible universal BEC regimes.

Contribution

The paper presents the first synthesis of single crystals of Sr3Cr2O8 and identifies it as a new realization of triplon BEC with accessible universal regimes at experimentally reachable temperatures.

Findings

Magnetic order observed between 30.4 T and 62 T.

Order persists up to approximately 8 K at 44 T.

The phase boundary follows a 3D BEC universality class with v=0.65(2).

Abstract

Single crystals of the spin dimer system Sr3Cr2O8 have been grown for the first time. Magnetization, heat capacity, and magnetocaloric effect data up to 65 T reveal magnetic order between applied fields of Hc1 ~ 30.4 T and Hc2 ~ 62 T. This field-induced order persists up to ~ 8 K at H ~ 44 T, the highest observed in any quantum magnet where Hc2 is experimentally-accessible. We fit the temperature-field phase diagram boundary close to Hc1 using the expression Tc = A(H-Hc1)^v. The exponent v = 0.65(2), obtained at temperatures much smaller than 8 K, is that of the 3D Bose-Einstein condensate (BEC) universality class. This finding strongly suggests that Sr3Cr2O8 is a new realization of a triplon BEC where the universal regimes corresponding to both Hc1 and Hc2 are accessible at He-4 temperatures.