Field induced phase transitions in the helimagnet Ba2CuGe2O7

Abstract

We present a theoretical study of the two-dimensional spiral antiferromagnet Ba2CuGe2O7 in the presence of an external magnetic field. We employ a suitable nonlinear sigma model to calculate the T=0 phase diagram and the associated low-energy spin dynamics for arbitrary canted fields, in general agreement with experiment. In particular, when the field is applied parallel to the c axis, a previously anticipated Dzyaloshinskii-type incommensurate-to-commensurate phase transition is actually mediated by an intermediate phase, in agreement with our earlier theoretical prediction confirmed by the recent observation of the so-called double-k structure. The sudden pi/2 rotations of the magnetic structures observed in experiment are accounted for by a weakly broken U(1) symmetry of our model. Finally, our analysis suggests a nonzero weak-ferromagnetic component in the underlying Dzyaloshinskii-Moriya anisotropy, which is important for quantitative agreement with experiment.

17 pages, 14 figures. Corrected typos in the abstract

References in corpus (2)

• Spontaneous Skyrmion Ground States in Magnetic Metals
• Magnetoelectric nature of skyrmions in a chiral magnetic insulator Cu2OSeO3

Cited by in corpus (10)

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• Formation of incommensurate long-range magnetic order in the Dzyaloshinskii-Moriya antiferromagnet Ba${}_2$CuGe${}_2$O${}_7$ studied by neutron diffraction
• Fingerprints of spin-current physics on magnetoelectric response in the spin-$1/2$ magnet Ba${}_2$CuGe${}_2$O${}_7$
• Infrared phonon spectrum of the tetragonal helimagnet Ba${}_2$CuGe${}_2$O${}_7$
• The effects of KSEA interaction on the ground-state properties of spin chains in a transverse field
• Synthesizing and Controlling Helical Indirect Exchange Interactions at Nonequilibrium
• Recognizing critical lines via entanglement in non-Hermitian systems
• Field-induced transitions from incommensurate to commensurate phases in helical antiferromagnets