Magnetocrystalline anisotropic effect in GdCo${}_{1-x}$Fe${}_x$AsO ($x=0,0.05$)

Abstract

From a systematic study of the electrical resistivity $\rho (T,H)$, magnetic susceptibility $\chi (T,H)$, isothermal magnetization $M(H)$ and the specific heat $C(T,H)$, a temperature-magnetic field ($T$-$H$) phase diagram has been established for GdCo${}_{1-x}$Fe${}_x$AsO ($x=0$ and $0.05$) polycrystalline compounds. GdCoAsO undergoes two long-range magnetic transitions: ferromagnetic (FM) transition of Co $3d$ electrons ($T_{\text{C}}^{\text{Co}}$) and antiferromagnetic (AFM) transition of Gd $4f$ electrons ($T_{\text{N}}^{\text{Gd}}$). For the Fe-doped sample ($x=0.05$), an extra magnetic reorientation transition takes place below $T_{\text{N}}^{\text{Gd}}$, which is likely associated with Co moments. The two magnetic species of Gd and Co are coupled antiferromagnetically to give rise to ferrimagnetic (FIM) behavior in the magnetic susceptibility. Upon decreasing the temperature ($T<T_{\text{C}}^{\text{Co}}$), the magnetocrystalline anisotropy breaks up the FM order of Co by aligning the moments with the local easy axes of the various grains, leading to a spin reorientation transition at $T_{\text{R}}^{\text{Co}}$. By applying a magnetic field, $T_{\text{R}}^{\text{Co}}$ monotonically decreases to lower temperatures, while the $T_{\text{N}}^{\text{Gd}}$ is relatively robust against the external field. On the other hand, the applied magnetic field pulls the magnetization of grains from the local easy direction to the field direction via a first-order reorientation transition, with the transition field ($H_{\text{M}}$) increasing upon cooling the temperature.

accepted by physical Review B 6 figures and 7 pages

References in corpus (12)

• Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAs{O}_{1-x}{F}_x$
• Superconductivity at 41 K and its competition with spin-density-wave instability in layered CeO${}_{1-x}$F${}_x$FeAs
• Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
• Superconductivity in iron-based F-doped layered quaternary compound Nd[O1-xFx]FeAs
• Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO
• Superconductivity induced by cobalt doping in iron-based oxyarsenides
• Effect of Co doping on superconductivity and transport properties in SmFe${}_{1-x}$Co${}_x$AsO
• Interplay of Rare Earth and Iron magnetism in RFeAsO with R = La, Ce, Pr, and Sm: A muon spin relaxation study and symmetry analysis
• CeFePO: A Heavy Fermion Metal with Ferromagnetic Correlations
• The crystalline electric field as a probe for long range antiferromagnetic order and superconductivity in CeFeAsO${}_{1-x}$F${}_x$
• Ferromagnetism and superconductivity in P-doped CeFeAsO
• Ferromagnetic Quantum Critical Point in Heavy-Fermion Iron Oxypnictide Ce(Ru${}_{1-x}$Fe${}_x$)PO