tailieunhanh - Phase transition behaviour of ising spin glass on the FCC lattice

In this work, we study the nature of phase transition in a face centered cubic (FCC) antiferromagnet with Ising spins. The spin-glass character depends on the concentration p of ferromagnetic bonds randomly generated into the system. We introduce a new quantity MQ combined by the Edwards-Anderson order parameter Q and the standard magnetization M. | Communications in Physics, Vol. 23, No. 3 (2013), pp. 227-234 PHASE TRANSITION BEHAVIOUR OF ISING SPIN GLASS ON THE FCC LATTICE NGO VAN THANH Institute of Physics, Vietnam Academy of Science and Technology, 10 Dao Tan, Ba Dinh, Hanoi, Vietnam HOANG DINH TIEN High School for Gifted Students, Vinh University, 182 Le Duan, Vinh city, Nghe An province, Vietnam DIEP THE HUNG Cergy-Pontoise University, CNRS UMR 8089 2, Avenue Adolphe Chauvin, 95302 Cergy-Pontoise Cedex, France Email: nvthanh@ Received 09 July 2013; Accepted for publication 31 August 2013 Abstract. In this work, we study the nature of phase transition in a face centered cubic (FCC) antiferromagnet with Ising spins. The spin-glass character depends on the concentration p of ferromagnetic bonds randomly generated into the system. We introduce a new quantity MQ combined by the Edwards-Anderson order parameter Q and the standard magnetization M . Note that, it is impossible to obtain the susceptibility defined by the variance of Q or M , but we can do that for MQ . Using the standard Monte-Carlo and powerful Wang-Landau flat-histogram methods, we carry out in this work intensive simulations with many value of p. We show that the first-order transition has been destroyed with a tiny amount of ferromagnetic bond p ∼ . With increasing p, the antiferromagnetic phase changes into a spin glass, and then to ferromagnetic phase. I. INTRODUCTION A spin glass is a disordered magnet with random interactions, both ferromagnetic and also antiferromagnetic bonds are randomly distributed with comparable frequency. The term ”glass” comes from an analogy between the magnetic disorder in a spin glass and the positional disorder of a conventional, chemical glass, a window glass. Spin glasses have many metastable structures, so it is very difficult to explore experimentally or in simulations. Phase transition in spin glasses is a subject of intensive investigation since four decades. The main difficulties in .