In this paper, the entanglement in one-dimensional random XY spin system with Dzyaloshinskii-Moriya interaction is investigated, for which the impurities of exchange couplings and the external magnetic fields are considered as random Gaussian distribution variables. By solving the different spin-spin correlation functions and the average magnetization per spin, the concurrence is found. The results show that the Gaussian distribution and Dzyaloshinskii-Moriya interaction have considerable effect on the entanglement near particular locations of the system. Moreover, the entanglement can be controlled and enhanced by varying the distributions of the impurities, the strength of external magnetic field and Dzyaloshinskii-Moriya interaction.
Recently, Mazhar Ali ( Phys. Rev. A , 81 (2010) 042303 and J. Phys. B , 43 (2010) 045504) showed the phenomenon of distillability sudden death (DSD) in qutrit-qutrit systems under amplitude damping. In this paper, the phenomenon of distillability sudden death in two-qutrit systems which are in the presence of the external magnetic field and Dzyaloshinskii-Moriya (DM) interaction under decoherence has been investigated. With the help of the realignment criterion, we show that certain initial prepared free entangled states may become bound entangled states in a finite time. Moreover, the effects of the external magnetic field strength and the DM interaction parameter, as well as the intrinsic decoherence parameter on the possibility of DSD in our model have been studied in detail.
We investigate the interplay of Dzyaloshinskii-Moriya interactions and an external field in spin-
1∕2 dimers. For isolated dimers and at low field, we derive simple expressions for the staggered and uniform magnetizations which show that the orientation of the uniform magnetization can deviate significantly from that of the external field. In fact, in the limit where the
D vector of the Dzyaloshinskii-Moriya interaction is parallel to the external field, the uniform magnetization actually becomes perpendicular to the field. For larger fields, we show that the staggered magnetization of an isolated dimer has a maximum close to one-half the polarization, with a large maximal value of $0.35g{\ensuremath{\mu}}_{B}$ in the limit of very small Dzyaloshinskii-Moriya interaction. We investigate the effect of interdimer coupling in the context of ladders with density-matrix renormalization-group (DMRG) calculations and show that, as long as the values of the Dzyaloshinskii-Moriya interaction and of the exchange interaction are compatible with respect to the development of a staggered magnetization, the simple picture that emerges for isolated dimers is also valid for weakly coupled dimers with minor modifications. The results are compared with torque measurements on
Cu2(C5H12N2)2Cl4.