Stabilization of Néel order in frustrated magnets with increasing magnetic field

• Published in: EPJ Web of conferences 2013, Vol.40, p.4001-np
• Main Authors: Schmidt, Burkhard, Siahatgar, Mohammad, Thalmeier, Peter
• Format: Article
• Language: English
• Subjects: Field strength; Frustration; Magnetic fields; Magnets; Mathematical models; Order disorder; Quantitative analysis
• ISSN: 2100-014X; 2100-014X
• DOI: 10.1051/epjconf/20134004001

For low-dimensional frustrated quantum magnets, the dependence of the staggered moment ms on a magnetic field is nonmonotonic: For small and intermediate fields, quantum fluctuations are gradually suppressed, leading to an increase of m sub(s) (H). For large applied magnetic fields however, the classically expected monotonous decrease is recovered. For the same reasons, the Neel ordering temperature T sub(N) of such compounds first increases and then exhibits a reentrant behavior as a function of the field strength. The quantitative analysis of this behavior is an excellent tool to determine the frustration parameter of a given compound. We have derived a general linear spin-wave (LSW) theory in the presence of a magnetic field. Based on our LSW theory, including a small interlayer coupling, we use a self-consistent approach determining T sub(N) by the condition of a vanishing total moment. We apply our findings to the recently measured field dependence of the magnetic ordering temperature T sub(N) of Cu(pz) sub(2) (CIO sub(4)) sub(2) in the framework of the S = 1/2 two-dimensional J sub(1)-J sub(2) Heisenberg model. The observed increase with increasing field strength can be understood naturally using an intermediate frustration ratio J sub(2)/J sub(2) [approx =] 0.2, which is in accordance with the field dependence of the staggered moment.