Magnetic entropy change in a two-dimensional antiferromagnetic square lattice


Gencer H.

INTERNATIONAL JOURNAL OF MODERN PHYSICS B, cilt.20, sa.18, ss.2527-2536, 2006 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 20 Sayı: 18
  • Basım Tarihi: 2006
  • Doi Numarası: 10.1142/s0217979206034868
  • Dergi Adı: INTERNATIONAL JOURNAL OF MODERN PHYSICS B
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.2527-2536
  • İnönü Üniversitesi Adresli: Evet

Özet

In this study, we investigate magnetic entropy variation and magnetocaloric properties as a function of frustration by considering a spin-1/2 antiferromagnetic Heisenberg model on a square lattice with nearest (J(1)) and next-nearest neighbor exchange interaction (J(2)). We show that the degree of frustration in the square lattice increases with alpha = J(2)/J(1). While the square lattice is unfrustrated for alpha = 0, it becomes fully frustrated for alpha = 0.5. Numerical results show that the entropy of the square lattice approaches zero for the unfrustrated case at T = 1 K. In contrast, finite entropy can survive in the frustrated case at the same temperature. We also calculate the magnetic entropy change (Delta S-m) in the square lattice and show that the maximum value of Delta S-m increases with increasing alpha. These results indicate that the magnetic entropy change and consequently the magnetocaloric effect can be enhanced by increasing the degree of frustration. We conclude that the enhanced magnetocaloric effect is related to quantum fluctuations and disordered ground state present in the frustrated square lattice.