Magnetic phase transition and critical phenomena

I have investigated phase transitions and critical properties in magnets. Specifically, using quantum Monte Carlo simulations, we have studied the spin-flop transitions in two- and three-dimensional XXZ models with Ising-like anisotropy, which are equivalent to the superfluid-insulator transitions in hard-core bose Hubbard models with large nearest-neighbor repulsions [1]. Critical properties of the magnetic phase transition in the ferrimagnet Sr₈CaRe₃Cu₄O₂₄ have also been investigated by using numerical simulations [2,3]. For impurity effects on frustrated magnets, we have theoretically shown that an infinitesimal density of impurities causes a macroscopic reduction of magnetization in one-dimensional frustrated ferro- and ferrimagnets [4].

[Related papers]

• "Magnetization process of the spin-1/2 XXZ models on square and cubic lattices",
  Masanori Kohno, and Minoru Takahashi,
  Physical Review B 56, pp.3212-3217 (1997).
• "Magnetic and electronic properties of the new ferrimagnet Sr₈CaRe₃Cu₄O₂₄",
  Masanori Kohno, Xiangang Wan, and Xiao Hu,
  Materials Science Poland, 23, pp.375-382 (2005).
• "Orbital order and ferrimagnetic properties of the new compound Sr₈CaRe₃Cu₄O₂₄",
  Xiangang Wan, Masanori Kohno, and Xiao Hu,
  Physical Review Letters 94 087205 (2005).
• "Anomalous impurity effect on magnetization in frustrated one-dimensional ferro- and ferrimagnets",
  Masanori Kohno, and Xiao Hu,
  Physical Review B 76 174409 (2007).