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Séminaire MCBT : vendredi 17 juin 2022 à 11h00

Kohama Yoshimitsu (ISSP Tokyo)

Titre : High-field calorimetric study of the hidden state in SrCu2(BO3)2


Institut Néel, Salle M200 (Rammal Rammal)
Résumé : SrCu2(BO3)2 is an exciting material that shows the sequence of magnetization plateaus and possible supersolid states under high magnetic fields [1]. To understand its exotic feature just below the magnetization plateaus, we have investigated the temperature dependence of the magnetic entropy in SrCu2(BO3)2 up to 30 T by using  specific heat [2] and magnetocaloric effect measurements [3]. Our study reveals the emergence of a broad anomaly in Cp and large magnetic entropy in the intermediate field range from 24 to 27 T [4]. This anomaly can neither be attributed to the 1st order phase transition to the magnetization plateau nor Schottky anomaly [1]. Since there is no internal field observed in NMR [1] for the intermediate field range, we interpret these anomalies as the crystallization or Bose-Einstein condensation of the Sz = 2 state.
[1] K. Kodama et al., Science 298, 395-399 (2002).
[2] S. Imajo et al., Rev. Sci. Instrum. 92, 043901 (2021).
[3] T. Kihara et al., Rev. Sci. Instrum. 84, 074901 (2013).
[4] S. Imajo et al., arXiv: 2203. 07607.
[5] Hiroyuki Tsujii et al., J. Phys. Soc. Jpn. 80, 043707 (2011).