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Zero-point entropy of the spinel spin glasses CuGa2O4 and CuAl2O4

Fenner, LA; Wills, AS; Bramwell, ST; Dahlberg, M; Schiffer, P; (2009) Zero-point entropy of the spinel spin glasses CuGa2O4 and CuAl2O4. HIGHLY FRUSTRATED MAGNETISM 2008 (HFM 2008) , 145 , Article 012029. 10.1088/1742-6596/145/1/012029. Gold open access


The zero-point entropy of a spin glass is a difficult property to experimentally determine and interpret. Spin glass theory provides various predictions, including unphysical ones, for the value of the zero-point entropy, however experimental results have been lacking. We have investigated the magnetic properties and zero-point entropy of two spina Cu2+ based spin glasses, CuGa2O4 and CuAl2O4. Dc- and ac-susceptibility. The spin glass freezing temperature is determined to be T-f = 2.89 +/- 0.05 K for CuGa2O4 and T-f = 2.30 +/- 0.05 K for CuAl2O4. By integrating of S0 = 4.96 JK(-1)mol(-1) and S-0 = 4.76 JK(-1)mol(-1) respectively. These values are closest to the prediction for a Sherrington-Kirkpatrick XY spin glass, however they are notably higher than all of the theorectical predictions. This indicates that CuGa2O4 and CuAl2O4 have a greater degeneracy in their ground states than any of the spin glass models.

Type: Article
Title: Zero-point entropy of the spinel spin glasses CuGa2O4 and CuAl2O4
Location: Technische Univ, Braunschweig, GERMANY
Open access status: An open access publication
DOI: 10.1088/1742-6596/145/1/012029
URI: http://discovery.ucl.ac.uk/id/eprint/168244
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