We report the experimental observation of spin reorientation in the double perovskite Ho2FeCoO6. The magnetic phase transitions in this compound are characterized and studied through magnetization and specific heat, and the magnetic structures are elucidated through neutron powder diffraction. Two magnetic phase transitions are observed in this compound-one at K, from paramagnetic to antiferromagnetic, and the other at K, from a phase with mixed magnetic structures to a single phase through a spin reorientation process. The magnetic structure in the temperature range 200–45 K is a mixed phase of the irreducible representations and , both of which are antiferromagnetic. The phase with mixed magnetic structures that exists in Ho2FeCoO6 gives rise to a large thermal hysteresis in magnetization that extends from 200 K down to the spin reorientation temperature. At T N2, the magnetic structure transforms to . Though long-range magnetic order is established in the transition metal lattice, it is seen that only short-range magnetic order prevails in the Ho3+ lattice. Our results should motivate further detailed studies on single crystals in order to explore the spin reorientation process, spin switching and the possibility of anisotropic magnetic interactions giving rise to electric polarization in Ho2FeCoO6.

https://iopscience.iop.org/article/10.1088/1361-648X/aa919e/pdf

Spin reorientation and disordered rare earth magnetism in Ho2FeCoO6.

Magnetocaloric effect and spin-phonon correlations in RFe0.5Cr0.5O3 (R = Er and Yb) compounds

We report the experimental observation of spin reorientation in the double perovskite Ho$_2$FeCoO$_6$. The magnetic phase transitions in this compound are characterized and studied through magnetization and specific heat, and the magnetic structures are elucidated by neutron powder diffraction. Two magnetic phase transitions are observed in this compound - one at $T_\mathrm{N1} \approx$ 250~K, from paramagnetic to antiferromagnetic, and the other at $T_\mathrm{N2} \approx$ 45~K, from a phase with mixed magnetic structures to a single phase through a spin reorientation process. The magnetic structure in the temperature range 200~K - 45~K is a mixed phase of the irreducible representations $\Gamma_1$ and $\Gamma_3$, both of which are antiferromagnetic. The phase with mixed magnetic structures that exists in Ho$_2$FeCoO$_6$ gives rise to a large thermal hysteresis in magnetization that extends from 200~K down to the spin reorientation temperature. At $T_\mathrm{N2}$, the magnetic structure transforms to $\Gamma_1$. Though long-range magnetic order is established in the transition metal lattice, it is seen that only short-range magnetic order prevails in Ho$^{3+}$ - lattice. Our results should motivate further detailed studies on single crystals in order to explore spin reorientation process, spin switching and the possibility of anisotropic magnetic interactions giving rise to electric polarization in Ho$_2$FeCoO$_6$.

Spin reorientation and disordered rare earth magnetism in Ho$_2$FeCoO$_6$

We present the results on the order of phase transition around the spin re-orientation region using isothermal magnetization data performed on the sol-gel synthesized disordered double perovskite oxides Sm2FeCoO6 and Dy2FeCoO6 by Arrott plot method. The temperature variation of the DC magnetization data of both the samples show that there are two magnetic phase transitions; one at high temperature regime, the conventional paramagnetic (PM) to ferro or ferrimagnetic (FM or FIM) and the other at low temperatures, ferro or ferrimagnetic (FM or FIM) to antiferromagnetic (AFM). From the Arrott plot method, it is inferred that spin re-orientation transitions of both the compounds has a first order nature corresponding to the FM (FIM) to AFM transition.

/pdf/the-order-of-magnetic-phase-transitions-in-disordered-double-409aj9sqo1.pdf

The order of magnetic phase transitions in disordered double perovskite oxides Sm2FeCoO6 and Dy2FeCoO6

Evidence for weak ferromagnetism and metamagnetic phase transitions in frustrated antiferromagnetic systems with octahedral structure

The temperature dependent structural studies carried out on the spin-correlated system A2FeCoO6 (A= Sm, Eu, Dy and Ho) or AFCO (A= Sm, E, D and H), using synchrotron radiation is presented. Owing to the large absorption cross-sections of the rare earths; Eu, Sm and Dy for neutrons, synchrotron radiation is one of the best available candidates for probing the system. The perovskite phase formation is inferred from laboratory XRD with Cu Kα source. The temperature dependent synchrotron X-ray diffraction (SXRD) experiments show the coexistence of monoclinic P21/n and orthorhombic Pbnm phases in Ho and Dy, while Eu and Sm are formed in single phase Pbnm. The temperature dependent DC magnetization measurements infer the presence of many interesting features such as thermal hysteresis, magnetic irreversibility, spin re-orientation, re-entrant magnetization and negative magnetization.

/pdf/temperature-dependent-structural-studies-on-the-spin-1x37v6kmu8.pdf

A. K. Sinha

Papers

Temperature dependent structural studies on the spin correlated system A2FeCoO6 (A= Sm, Eu, Dy and Ho) using synchrotron radiation