Mapping the magnetic phase diagram of the frustrated metamagnetCuFeO2

Abstract

The magnetic phase diagram of CuFeO2 as a function of applied magnetic field and temperature is thoroughly explored and expanded, both for magnetic fields applied parallel and perpendicular to the material's c-axis. Pulsed field magnetization measurements extend the typical magnetic staircase of CuFeO2 at various temperatures, demonstrating the persistence of the recently discovered high field metamagnetic transition up to TN2 ≈ 11 K in both field configurations. An extension of the previously introduced phenomenological spin model used to describe the high field magnetization process (Phys. Rev. B, 80, 012406 ( 2009)) is applied to each of the consecutive low-field commensurate spin structures, yielding a semi-quantitative simulation and intuitive description of the entire experimental magnetization process in both relevant field directions with a single set of parameters.

Anisotropic lattice dynamics and intermediate-phase magnetism in delafossiteCuFeO2

“…In particular, magnetoelastic coupling can reduce the slope of the acoustic phonon dispersion branches [56] in the energy region well below 3 meV, which, in turn, would result in an increased "Debye level" at low phonon energies. Thus, the considerable underestimation of the average phonon group velocity by means of NIS may point towards a significant spinphonon coupling, which was already shown to be necessary in order to model the magnetic behavior [3,21] of CuFeO 2 . In addition to ultrasound-based investigations [22,23], the present results concerning the low-energy region indicate that magnetoelastic coupling persists in the paramagnetic phase of CuFeO 2 as well.…”

“…Besides, the layered structure of CuFeO 2 suggests a pronounced vibrational anisotropy, which is yet to be confirmed. Furthermore, in contrast to the magnetic ground state at zero magnetic field and magnetic phases at high fields, which generally exhibit rather well defined spin structures [3,4], the magnetic ITP has received considerably less attention and is not yet convincingly described.…”

“…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]. The relevance of the coupling between vibrational properties and magnetic degrees of freedom for both zero field phase transitions in CuFeO 2 was also pointed out in Refs.…”

“…The magnetic phase diagram of CuFeO 2 proves to be particularly rich with various magnetic phases at low temperatures, high magnetic fields [1][2][3][4], and high pressures [5,6]. Ferroelectricity [7] in CuFeO 2 and its connection to the magnetic order is the subject of ongoing studies [8,9].…”

High-pressure suppression of long-range magnetic order in the triangular-lattice antiferromagnetCuFeO2

“…Therefore, if the lattice distortion were suppressed by pressure, the magnetic LRO could not be stabilized and novel magnetic states such as spin liquids [5] and spin nematics [6,7] would be expected. In the present study, we examined the effect of pressure on magnetic ordering in the frustrated spin-lattice coupling system of CuFeO 2 .Since the discovery of the spontaneous spin-lattice coupling phenomenon in the frustrated triangular lattice antiferromagnet CuFeO 2 , [8,9] spin-lattice coupling has been extensively studied using high-field X-ray diffraction, [10, 11] ultrasonic velocity,[12] magnetization measurements, [13] and Landau theory approaches. [14] These studies have demonstrated that spontaneous spinlattice coupling plays an essential role in the stabilization of the magnetic ground state of CuFeO 2 .…”