Specific Heats of Triangular Spin Tube in Magnetic Fields

Abstract

In this study, the temperature (T) dependence of specific heat (Cp) is investigated in an equilateral triangular spin tube CsCrF4 above T = 0.38K under several magnetic fields (B). At B = 0 T, no λ-type anomaly of the temperature dependence [Cp(T)] appears over the entire temperature range. However, the DC and AC magnetic susceptibilities exhibit a small anomaly, which is interpreted as an antiferromagnetic phase transition at TN∼4.5K. This difference may indicate that the large magnetic entropy at B = 0 T is spent far below TN, because a large fluctuated spin state due to geometrical spin frustration may have occurred at T = 0K. Under different magnetic fields, the Cp(T)/T curves present shoulders and/or broad peaks above B = 1 T. The electronic specific heat coefficient decreases with increasing B indicating that the magnetic ground state consists of an antiferromagnetic ordered state with large spin fluctuations, rather than a gapless spin-liquid state, and their fluctuations are sensitively suppressed by the magnetic fields.