Low-field Magnetic Anisotropy of Sr2IrO4

Magnetic anisotropy in strontium iridate (Sr2IrO4) is essential because of its strong spin–orbit coupling and crystal field effect. In this paper, we present a detailed mapping of the out-of-plane (OOP) magnetic anisotropy in Sr2IrO4 for different sample orientations using torque magnetometry measurements in the low-magnetic-field region before the isospins are completely ordered. Dominant in-plane anisotropy was identified at low fields, confirming the b axis as an easy magnetization axis. Based on the fitting analysis of the strong uniaxial magnetic anisotropy, we observed that the main anisotropic effect arises from a spin–orbit-coupled magnetic exchange interaction affecting the OOP interaction. The effect of interlayer exchange interaction results in additional anisotropic terms owing to the tilting of the isospins. The results are relevant for understanding OOP magnetic anisotropy and provide a new way to analyze the effects of spin–orbit-coupling and interlayer magnetic exchange interactions. This study provides insight into the understanding of bulk magnetic, magnetotransport, and spintronic behavior on Sr2IrO4 for future studies.

Synthesis, Crystal Structures, and Spectroscopic Properties of Novel Gadolinium and Erbium Triphenylsiloxide Coordination Entities

In alkali metal and lanthanide coordination chemistry, triphenylsiloxides seem to be unduly underappreciated ligands. This is as surprising as that such substituents play a crucial role, among others, in stabilizing rare oxidation states of lanthanide ions, taking a part of intramolecular and molecular interactions stabilizing metal-oxygen cores and many others. This paper reports the synthesis and characterization of new lithium [Li4(OSiPh3)4(THF)2] (1), and sodium [Na4(OSiPh3)4] (2) species, which were later used in obtaining novel gadolinium [Gd(OSiPh3)3(THF)3]·THF (3), and erbium [Er(OSiPh3)3(THF)3]·THF (4) triphenylsiloxides. Crystal structures were determined for all 1–4 compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for 3 and 4 lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3 and 4 were carried out in the temperature range 1.8–300 K. The 3 shows behavior characteristics for the paramagnetism of the Gd3+ ion. In contrast, the magnetic properties of 4 are dominated by the crystal field effect on the Er3+ ion, masking the magnetic interaction between magnetic centers of neighboring molecules.

Microstructure, magnetic and electronic transport properties of reactively facing-target sputtered epitaxial Mn4N films

The structure, magnetic and electronic transport properties of epitaxial Mn4N films fabricated by the facing-target reactive sputtering method have been investigated systematically. The high-quality growth of Mn4N films was confirmed by X-ray θ-2θ, pole figures and high-resolution transmission electron microscopy. The Mn4N films exhibit ferrimagnetic with strong perpendicular magnetic anisotropy. The saturation magnetization of Mn4N films decreases with increasing temperature, following the Bloch’s spin wave theory. The resistivity of Mn4N films exhibits metallic conductance mechanism. Debye temperature of Mn4N is estimated to be 85 K. The calculated residual resistivity ρxx0 of the 78.8 nm-thick Mn4N film is 30.56 μΩ cm. The magnetoresistances of Mn4N films display a negative signal and butterfly shape. The sign of anisotropic magnetoresistance (AMR) is positive, which infers that the AMR is dominated by the spin-up conduction electrons. Moreover, the transformation of fourfold to twofold symmetry for AMR and twofold to onefold symmetry for planar Hall resistivity is attributed to tetragonal crystal field effect.

Low-Field Magnetic Anisotropy of Sr2IrO4

Magnetic anisotropy in strontium iridate (Sr2IrO4) is essential because of its strong spin-orbit coupling and crystal field effect. In this study, we investigated the detailed mapping of the out-of-plane (OOP) magnetic anisotropy in Sr2IrO4 for different sample orientations using torque magnetometry measurements in the low-magnetic-field region before the isospins are fully ordered. Dominant in-plane anisotropy was identified at low fields, confirming the b axis as an easy magnetization axis. Based on the fitting analysis of the strong uniaxial magnetic anisotropy, we observed that the main anisotropic effect arises from a spin–orbit-coupled magnetic exchange interaction that affects the OOP interaction. The interlayer exchange interaction results in additional anisotropic terms owing to the tilting of the isospins. Our results are relevant for understanding OOP magnetic anisotropy and provide a new way to analyze the effects of spin–orbit-coupling and interlayer magnetic exchange interactions. This study provides a new insight into the understanding of bulk magnetic, magneto-transport, and spintronic behavior of Sr2IrO4 for future studies.

Towards Kitaev spin liquid in 3d transition metal compounds

This paper reviews the current progress on searching the Kitaev spin liquid state in 3[Formula: see text] electron systems. Honeycomb cobaltates were recently proposed as promising candidates to realize the Kitaev spin liquid state, due to the more localized wavefunctions of [Formula: see text] ions compared with that of [Formula: see text] and [Formula: see text] ions, and also the easy tunability of the exchange Hamiltonian in favor of Kitaev interaction. Several key parameters that have large impacts on the exchange constants, such as the charge-transfer gap and the trigonal crystal field, are identified and discussed. Specifically, tuning crystal field effect by means of strain or pressure is emphasized as an efficient phase control method driving the magnetically ordered cobaltates into the spin liquid state. Experimental results suggesting the existence of strong Kitaev interactions in layered honeycomb cobaltates are discussed. Finally, the future research directions are briefly outlined.

Magnetic properties of organolanthanide(II) complexes, from electronic structure and crystal field effect

Magnetic properties of a series of organometallic complexes [LnCp3 ]- and Ln(CNT)2, were Cp =cyclopentadienyl and CNT = ciclononatetraenyl, of the lanthanide ions in 2+ oxidation state, are theoretically studied...