We consider a deformable spin-1/2 antiferromagnetic XXZ Heisenberg chain and examine the spin-chain lattice compressibility as well as the sound velocity as a function of an external magnetic field applied either along the z axis or along the x axis. For strong fields, we observe a noticeable increase (with jump and hysteresis) of the lattice compressibility. Our findings are obtained by several complimentary approaches (Jordan-Wigner…
Localised quasiclassical states in asymptotic theory of ion-atom interactions
The interest to the study of localised states in atomic physics is, on the one hand, evoked by the fact, that in the numerous cases their analysis can be carried out analytically. Such method belongs to not much approaches, which allow investigating the system with nonfactorised variables without the use of perturbation theory or cumbersome numerical methods. On the other hand, the aforementioned states often…
One-Way Transfer of Magnetic Fields
Researchers have created a material that acts as a magnetic diode, transferring magnetism from one object to another but not the other way around. An electric current flowing through a coil of copper wire induces a magnetic field in the coil. This magnetic field can then transfer to a nearby magnetic object, such as a second coil of wire. The laws of electromagnetism, and experimental…
Effects of higher-order exchange interactions in classical XY model
A standard two-dimensional (2D) XY model is well known to show a topological Berezinskii-Kosterlitz-Thouless (BKT) phase transition with the quasi-long-range-order (QLRO) BKT phase characterized by an algebraically decaying correlation function. It will be shown by spin-wave theory and Monte Carlo simulations that including higher-order terms can lead to dramatic changes in its critical behavior, including phase transition order or universality class and even the phase…