Pamella Vasconcelos Borges Pinho

arXiv2025

Magnetic behavior and phase diagram of epitaxial Er3Fe5O12 thin films across the compensation temperature

Rare-earth iron garnet (RE3Fe5O12) films are promising insulating ferrimagnets. They can show low magnetic damping, perpendicular magnetic anisotropy, and ultrafast spin dynamics, which makes them ideal for spin transport applications. In this work, we investigate the interaction between the magnetic sublattices in Er3Fe5O12 thin films grown by pulsed laser deposition on a Gd3Ga5O12 substrate. Structural and magnetic characterization reveals high-quality single-crystal growth, with compensation temperature close to the reported bulk value (~80 K). Magnetic phase diagrams based on element-specific measurements map out the regions where ferrimagnetic, canted, and aligned phases are stable across the compensation temperature. The micromagnetic dynamics resulting from perpendicular magnetic pulse perturbation of an in-plane magnetized layer was investigated at room temperature and reveals complex configurations. These results are a key feature for modulating magnetization dynamics through the compensation phenomenon, which is essential for spin-based devices operating in a low-temperature regime.

cond-mat.mtrl-sci↗

arXiv2025

In situ growth and magnetic characterization of Cr Chloride monolayers

Monolayer Chromium Dihalides and Trihalides materials can be grown on a variety of substrates by molecular beam epitaxy regardless of the lattice mismatch thanks to the van der Waals epitaxy. In this work, we studied the magnetic nature of Cr Chloride monolayers grown on Au(111), Ni(111) and graphene-passivated Ni(111) from the evaporation in ultra-high vacuum of the same halide precursor. Structural, morphological and magnetic characterizations were conducted in situ by low energy electron diffraction (LEED), scanning tunneling microscopy (STM) and X-ray magnetic circular dichroism (XMCD). Owing to opposite chemical behaviour, Au(111) and Ni(111) promote the formation of two different valence compounds, i.e. CrCl$_3$ and CrCl$_2$, showing distinct magnetic properties at 4 K. When graphene is used to passivate the Ni(111) surface, the formation of CrCl$_3$ becomes allowed also on this substrate. The coexistence of CrCl$_3$ and CrCl$_2$, both showing few nm lateral size and super-paramagnetic properties, is demonstrated by XMCD spectra displaying two dichroic peaks at the characteristic Cr$^{3+}$ and Cr$^{2+}$ energies. Site-selective magnetization measurements performed with the photon energy tuned on the two absorption edges show reversed magnetization of some of the CrCl$_2$ islands with respect to the CrCl3 domains, which is interpreted in terms of magnetic frustration.

cond-mat.mtrl-sci↗