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José Laurentino

Publications and source records attributed to José Laurentino.

3 recordsLinked to original sources

Unifying Magnetic, Electrical, and Thermoelectric Responses in a Non-Collinear Antiferromagnet

Non-collinear antiferromagnets offer unconventional routes for controlling magnetic, electrical, and thermoelectric responses through their complex spin configurations and interfacial symmetry. Here, we detect exceptional interfacial properties arising from a non-collinear antiferromagnet by demonstrating a robust and quantitatively consistent exchange-bias response in an IrMn$_3$/Py heterostructure. The system consists of a 10 nm IrMn$_3$ layer coupled to a 5 nm permalloy (Py) film. Longitudinal magneto-optical Kerr effect (MOKE), anisotropic magnetoresistance (AMR), and anomalous Nernst effect (ANE) measurements independently reveal the same unidirectional field shift of approximately 50 Oe, together with a consistent cosine angular dependence. The simultaneous observation of these signatures establishes a direct correspondence between the interfacial magnetic symmetry imposed by the non-collinear antiferromagnet and the responses of the adjacent ferromagnet. This symmetry is manifested consistently in magnetization reversal, charge transport, and thermally driven voltage generation, demonstrating that the exchange-bias imprint is not restricted to a single experimental observable. Our results reveal a coherent multifunctional response of IrMn$_3$/Py and extend the conventional understanding of exchange bias beyond collinear antiferromagnetic systems. More broadly, they demonstrate the potential of non-collinear antiferromagnets as platforms for coupling magnetic, electrical, and thermoelectric functionalities in spintronic and spin-caloritronic devices.

cond-mat.mtrl-sci↗

Controlling magnetic damping with spintronic thermal effects in Py/Fe3O4-PANI bilayers

We report experiments that control magnetic damping in Py/Fe3O4-PANI via two spintronic thermal effects: spin Seebeck and anomalous Nernst. Magnetic damping is measured using ferromagnetic resonance (FMR) techniques, where the sample is excited by microwave radiation and the resulting DC voltage is detected in the Fe3O4-PANI film. When a temperature gradient is applied in the longitudinal configuration, the DC voltage linewidth increases or decreases depending on the direction of the thermal gradient. This finding demonstrates that magnetic damping in Py/Fe3O4-PANI can be controlled by currents induced by thermal effects. Remarkably, the absolute linewidth changes observed in Py/Fe3O4-PANI exceed those seen in bilayers of ferrimagnetic insulator yttrium iron garnet and heavy metal by more than an order of magnitude. We interpret the significant change in magnetic damping as a result of intrinsic phenomena occurring in bilayers.

cond-mat.mtrl-sci↗

Observing a quantum magnetic effect in CaYAl3O7-X particles (X=Ni, Fe, Co)

Yttrium calcium aluminate, with the formula CaYAl3O7, has been extensively researched due to its remarkable luminescent properties when doped or co-doped. Additionally, it exhibits exceptional piezoelectric properties at high temperatures. However, the potential magnetic properties this material can acquire through doping or co-doping have largely gone unexplored until now. In this innovative study, we investigate the quantum magnetic characteristics of yttrium calcium aluminate particles doped with transition metals such as cobalt, iron, and nickel. Our magnetic measurements of hysteresis curves in the macroscopic regime reveal intriguing magnetic characteristics that have not been documented in the literature. Given the high applicability of this material in biological microelectromechanical systems, we conducted a detailed study to demonstrate these findings.

cond-mat.mtrl-sci↗