The influence of magnetic field on the two-dimensional quantum antiferromagnet Cu(tn)Cl2: an intriguing magnetic phase diagram


The influence of magnetic field on the two-dimensional quantum antiferromagnet Cu(tn)Cl2: an intriguing magnetic phase diagram

Orendacova, A.; Cizmar, E.; Sedlakova, L.; Hanko, J.; Kajnakova, M.; Zelenak, V.; Xia, J. S.; Yin, L.; Pajerowski, D. M.; Zvyagin, S. A.; Wosnitza, J.; Orendac, M.; Feher, A.; Meisel, M. W.

Specic heat and magnetic susceptibility measurements, spanning low temperatures (T ≥ 40 mK) and high magnetic elds (B ≤ 14 T), have been performed on Cu(tn)Cl2 (tn = C3H10N2), a two-dimensional (2D) S = 1/2 spatially anisotropic triangular antiferromagnet realized by a square lattice with nearest- neighbor (J=kB = 3 K), frustrating next-nearest-neighbor (0 < J'/J < 0.6), and interlayer (|J''/kB| <3 mK) interactions [1]. The absence of long-range magnetic order down to T = 60 mK in B = 0 and the T2 behavior of the specific heat for T ≤ 0.4 K and B ≥ 0 are considered evidence of 2D magnetic correlations. In fields lower than the saturation field, Bsat = 6.6 T, a specific heat anomaly, appearing near 0.8 K, is interpreted as a Berezinski-Kosterlitz-Thouless (BKT) phase transition. The magnetic phase diagram is remarkably consistent with the theoretical predictions [2], except for the point that Bsat(T -> 0) is shifted to values significantly lower than expected. Potential explanations for this observation will be discussed.

  • Invited lecture (Conferences)
    QFS2009 - International Symposium on Fluids and Solids, 05.-11.08.2009, Evanston, Illinois, USA

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Publ.-Id: 13193