“Spin-Driven” Crystal Lattice Distortion in Frustrated Magnet CuFeO₂: Synchrotron X-ray Diffraction Study

Identification of microscopic spin-polarization coupling in the ferroelectric phase of magnetoelectric multiferroicCuFe1−xAlxO2Nakajima1, Mitsuda2, Inami3 et al. 2008Phys. Rev. BSelf Cite370331View full textAdd to dashboardCite

“…2, this system exhibits three magnetically ordered phases in zero field. For all the phases, the magnetic modulation wave vectors are described by (0, q, The monoclinic lattice distortions are also observed in the undiluted (x = 0.00) system, 21,22 in which the PD and FEIC phases show up as the thermally induced phase and the first field-induced phase, respectively. As discussed in the previous studies, 21,22,23 these structural transitions are due to the bond order induced by the magnetostriction, which leads to lower-symmetry magnetic orderings and lifts the macroscopic degeneracy of the magnetic states.…”

“…Taking into account the monoclinic lattice distortions found in the magnetically ordered phases of undiluted CuFeO 2 , 21,22,23 it is reasonable to employ a monoclinic basis in addition to the conventional hexagonal basis. The definitions of these bases are shown in Figs.…”

Anisotropic lattice dynamics and intermediate-phase magnetism in delafossiteCuFeO2

“…Each layer of magnetic Fe 3+ ions ( 6 S 5/2 ground state) constitutes a two-dimensional, triangular lattice, which in combination with antiferromagnetic interactions represents a classical case of geometric frustration. Despite its electronic configuration, which prima facie suggests isotropic antiferromagnetic exchange interactions, CuFeO 2 adopts a collinear, Ising-like magnetic structure at low temperatures below 11 K. In zero magnetic field, two structural [13,14] and magnetic transitions are observed at T N1 ≈ 14 K and T N2 ≈ 11 K. Structurally, CuFeO 2 transforms to space group C2/m at T N1 and to lower monoclinic symmetry at T N2 . Above T N1 , CuFeO 2 is paramagnetic (PM), whereas the magnetic structure in the intermediate temperature phase (ITP), i.e., T N2 < T < T N1 , is usually considered a quasi-long-range ordered, sinusoidally amplitude modulated, incommensurate structure with a temperature-dependent propagation vector [15] and a potential, residual paramagnetic contribution [16].…”

“…At T N2 , CuFeO 2 reaches its collinear foursublattice magnetic ground state (4SL) with spins aligned (anti)parallel along the c axis adopting an up-up-down-down order [17]. The stabilization of the Ising-like 4SL structure can be attributed to a low-temperature structural distortion resulting in unequal nearest-neighbor exchange interactions [13,14,18,19]. Alternatively, the distortion may yield a weak magnetic anisotropy [20], which in combination with a rather strong spin-phonon coupling can give rise to the Isinglike behavior [2,3,21].…”

Spin dynamics in the geometrically frustrated multiferroicCuCrO2

“…As shown Despite their inherent frustration, these systems find a way to lift their macroscopic degeneracy and to achieve a complex three-dimensional (3D) magnetic ordering below a Néel ordering temperature T N . In the case of CuFeO 2 a transition from the R − 3 m to C2/m symmetry is found to accompany the magnetic ordering ; this distortion is believed to help lifting the degeneracy of the frustrated magnetic lattice, to achieve an Ising-like 4-sublattice (↑↑↓↓) antiferromagnetic (AF) order at low temperature [3], [4], [5]. In CuCrO 2 , an incommensurate magnetic structure, derived from the classical 120° spin configuration expected for a perfect planar triangular antiferromagnet [6], has been reported [7], [8].…”