Biquadratic antisymmetric exchange and the magnetic phase diagram of magnetoelectric CuFeO${}_2$

Abstract

Biquadratic {\it antisymmetric} exchange terms of the form $-[C_{ij}{e}_{ij}^{\alpha }({\mathbf{s}}_i\times {\mathbf{s}}_j{)}_z{]}^2$, where ${\mathbf{e}}_{ij}$ is the unit vector connecting sites $i$ and $j$ and $\alpha =x,y$, due partially to magnetoelectric coupling effects, are shown to be responsible for the spin-flop helical phase in CuFeO${}_2$ at low magnetic field and temperature. Usual biquadratic {\it symmetric} exchange, likely due to magnetoelastic coupling, is found to support the stability of axial magnetic states at higher fields in this nearly-Heisenberg like stacked triangular antiferromagnet. A model Hamiltonian which also includes substantial interplane and higher-neighbor intraplane exchange interactions, reproduces the unique series of observed commensurate and incommensurate periodicity phases with increasing applied magnetic field in this highly frustrated system. The magnetic field-temperature phase diagram is discussed in terms of a Landau-type free energy.

7 pages, 9 figures

References in corpus (4)

• Spin current and magneto-electric effect in non-collinear magnets
• Magnetically driven ferroelectric order in Ni${}_3$V${}_2$O${}_8$
• Dynamical magneto-electric coupling in helical magnets
• Mechanisms of degeneracy breaking in pyrochlore antiferromagnets

Cited by in corpus (4)

• Spin phonon induced colinear order and magnetization plateaus in triangular and kagome antiferromagnets. Applications to CuFeO_2
• Nonlocal Landau theory of the magnetic phase diagram of highly frustrated magnetoelectric CuFeO${}_2$
• A model of magnetic order in hexagonal HoMnO3
• Transient selection of competing order in frustrated spin Peierls systems after a quench