Bose-Einstein condensation in quantum magnets

Abstract

This article reviews experimental and theoretical work on Bose-Einstein condensation in quantum magnets. These magnets are natural realizations of gases of interacting bosons whose relevant parameters such as dimensionality, lattice geometry, amount of disorder, nature of the interactions, and particle concentration can vary widely between different compounds. The particle concentration can be easily tuned by applying an external magnetic field which plays the role of a chemical potential. This rich spectrum of realizations offers a unique possibility for studying the different physical behaviors that emerge in interacting Bose gases from the interplay between their relevant parameters. The plethora of other bosonic phases that can emerge in quantum magnets, of which the Bose-Einstein condensate is the most basic ground state, is reviewed. The compounds discussed in this review have been intensively studied in the last two decades and have led to important contributions in the area of quantum magnetism. In spite of their apparent simplicity, these systems often exhibit surprising behaviors. The possibility of using controlled theoretical approaches has triggered the discovery of unusual effects induced by frustration, dimensionality, or disorder.

Field-Induced Magnonic Liquid in the 3D Spin-Dimerized AntiferromagnetSr3Cr2O8Wang1, Quintero-Castro2, Жерлицын3 et al. 2016Phys. Rev. Lett.182801View full textAdd to dashboardCite

“…Due to enhanced quantum fluctuations and reduced dimensionality, the low-dimensional quantum magnets host very often exotic quantum states of matter [1][2][3][4][5][6][7][8][9][10][11][12][13] . Especially for the one-dimensional (1D) spin systems, realization of novel quantum spin states is not only of lively experimental interest [7][8][9][10]12,13 but also a constant focus of theoretical study 1,2,[14][15][16][17] , since quantitative description of the elementary excitations can be provided by rigorous theoretical approaches and precise comparisons between theoretical predictions and experimental results can be made [7][8][9][10]12,13,15 .…”

Stabilization of the tetragonal structure in(Ba1−xSrx)CuSi2O6

“…The occurrence of magnetic fieldinduced ordered states, which can be described as BoseEinstein condensation (BEC) of triplons in this type of compounds provide a platform to study this ordered state in great detail, e.g., by investigating scaling laws of thermodynamic quantities [1]. The main idea behind this is that dimers of two Cu 2+ -ions, which each carry a spin 1/2, can be mapped onto bosons to realize a BEC [2].…”

Manifestation of magnetic quantum fluctuations in the dielectric properties of a multiferroic

“…The Fermi-liquid state of the conduction electrons shows instabilities near a magnetic QCP, often leading to non-Fermi-liquid behaviour and even exotic superconductivity 2,3 . In the absence of conduction electrons, a magnetic QCP has been found in Ising ferromagnets by applying a transverse magnetic field 4,5 and in spin-dimer compounds that show Bose-Einstein Condensation (BEC) [6][7][8] . QPT can also be found in ferroelectric (FE) materials where the electric polarization (P) serves as the order parameter.…”