Twisted phase of the orbital-dominant ferromagnet SmN in a GdN/SmN heterostructure

On the ferromagnetic ground state of SmN

SmN is a ferromagnetic semiconductor with the unusual property of an orbital-dominant magnetic moment that is largely cancelled by an antiparallel spin contribution, resulting in a near-zero net moment. However, there is a basic gap in the understanding of the ferromagnetic ground state, with existing density functional theory calculations providing values of the $4f$ magnetic moments at odds with experimental data. To clarify the situation, we employ an effective $4f$ Hamiltonian incorporating spin-orbit coupling, exchange, the crystal field, and $J$-mixing to calculate the ground state $4f$ …

Spin/orbit moment imbalance in the near-zero moment ferromagnetic semiconductor SmN

SmN is ferromagnetic below 27 K, and its net magnetic moment of 0.03 Bohr magnetons per formula unit is one of the smallest magnetisations found in any ferromagnetic material. The near-zero moment is a result of the nearly equal and opposing spin and orbital moments in the 6H5/2 ground state of the Sm3+ ion, which leads finally to a nearly complete cancellation for an ion in the SmN ferromagnetic state. Here we explore the spin alignment in this compound with X-ray magnetic circular dichroism at the Sm L2,3 edges. The spectral shapes are in qualitative agreement with computed spectra based on …

Epitaxial integration of the intrinsic ferromagnetic semiconductor GdN with silicon technology

A major challenge for the next generation of spintronics devices is the implementation of ferromagnetic-semiconductor thin films as spin injectors and detectors. Spin-polarised carrier injection cannot be accomplished efficiently from metals, and coupled with the rarity of intrinsic ferromagnetic semiconductors this has driven intensive study of diluted magnetic semiconductors. Chief among these is the doped III-V compound (Ga,Mn)As. These materials suffer from a number of drawbacks; they (i) require magnetic-ion doping well above the solubility limit, and (ii) must be hole doped to above the …

Microscopic properties of degradation-free capped GdN thin films studied by Electron Spin Resonance

The microscopic magnetic properties of high-quality GdN thin films have been investigated by electron spin resonance (ESR) and ferromagnetic resonance (FMR) measurements. Detailed temperature dependence ESR measurements have shown the existence of two ferromagnetic components at lower temperatures which was not clear from the previous magnetization measurements. The temperature, where the resonance shift occurs for the major ferromagnetic component, seems to be consistent with the Curie temperature obtained from the previous magnetization measurement. On the other hand, the divergence of line …

\textit{Additional} carrier-mediated ferromagnetism in GdN

The mechanism behind ferromagnetic exchange interaction in GdN is not well understood. It has been argued that it can be due to fourth order cross process of \textit{d-f} mixing and \textit{d-f} exchange. An alternative explanation suggests an anti- ferromagnetic interaction between Gd \textit{d} and N \textit{p} induced moments on the rock salt structure which aligns the nearest neighbor Gd \textit{f} moments ferromagnetically through the \textit{d-f} exchange. In this paper we present results of Curie temperature in GdN as a function of carrier density calculated within our multiband modifie…

氮空位介导的溅射GdN薄膜磁性

Nitrogen-Vacancy-Mediated Magnetism in Sputtered GdN Thin Films

研究通过溅射法制备GdN薄膜，发现氮空位介导的铁磁性增强，通过Raman模式与磁化率关联，验证了空位对磁性调控的关键作用。