arXiv subjects

Binoy K. Hazra

Publications and source records attributed to Binoy K. Hazra.

4 recordsLinked to original sources

arXiv2026

Antiphase boundary-driven large exchange bias and negative magnetoresistance in NiCo2O4

Nickel-based spinel oxide has recently attracted significant attention due to its remarkable magneto-transport properties, promising various spintronic applications. In this study, we observe an exchange bias effect, where the magnetic hysteresis loop shifts both horizontally and vertically when single-phase nanocrystalline NiCo2O4 is cooled in the presence of an external magnetic field. The magnitude of the exchange bias field is approximately 375 Oe at 5 K, and this effect disappears around 300 K. Furthermore, NiCo2O4 shows semiconducting behaviour in longitudinal resistivity and demonstrates a substantial negative magnetoresistance of ~31.5% at 10 K. The magnetoresistance exhibits a butterfly-shaped behaviour at low magnetic fields and becomes almost linear at high magnetic fields. A detailed analysis of the negative magnetoresistance and exchange bias reveals that both phenomena originate from the formation of antiphase boundaries in the as-synthesized NiCo2O4 sample, as confirmed by the high-resolution transmission electron micrograph.

cond-mat.mtrl-sci↗

arXiv2024

Realization of a Spin Glass in a two-dimensional van der Waals material

Recent advances in van der Waals (vdW) materials have sparked renewed interest in the impact of dimensionality on magnetic phase transitions. While ordered magnetic phases have been demonstrated to survive in the two-dimensional (2D) limit, the quest for a spin-glass with quenched magnetic disorder in lower dimensions has proven elusive. Here we show evidence of a spin-glass emerging from randomly distributed Fe atoms in Fe3GeTe2, the first time such a state has been reported in a vdW material. AC magnetic susceptibility displays a strong frequency dependence indicative of slow spin dynamics. Additional distinctive phenomena, including ageing, chaos, and memory effects, further substantiate the existence of a glassy state. Remarkably, we find that this state persists even in single-unit-cell thick Fe3GeTe2, thereby confirming the existence of a 2D spin-glass. The formation of spin-glass states via intercalation in vdW systems allows for highly tunable spin-glass states that are otherwise difficult to realize.

cond-mat.mes-hall↗

arXiv2022

Generation of out-of-plane polarized spin current by spin swapping

The generation of spin currents and their application to the manipulation of magnetic states is fundamental to spintronics. Of particular interest are chiral antiferromagnets that exhibit properties typical of ferromagnetic materials even though they have negligible magnetization. Here, we report the generation of a robust spin current with both in-plane and out-of-plane spin polarization in epitaxial thin films of the chiral antiferromagnet Mn3Sn in proximity to permalloy thin layers. By employing temperature-dependent spin-torque ferromagnetic resonance, we find that the chiral antiferromagnetic structure of Mn3Sn is responsible for an in-plane polarized spin current that is generated from the interior of the Mn3Sn layer and whose temperature dependence follows that of this layer's antiferromagnetic order. On the other hand, the out-of-plane spin polarized spin current is unrelated to the chiral antiferromagnetic structure and is instead the result of scattering from the Mn3Sn/permalloy interface. We substantiate the later conclusion by performing studies with several other non-magnetic metals all of which are found to exhibit out-of-plane polarized spin currents arising from the spin swapping effect.

cond-mat.mtrl-sci↗

arXiv2017

Synthesis, magnetic properties and electronic structure of S = 1/2 uniform spin chain system InCuPO5

We have studied the structural, magnetic properties, and electronic structure of the compound InCuPO5 synthesized by solid state reaction method. The structure of InCuPO5 comprises of S = 1/2 uniform spin chains formed by corner-shared CuO4 units. Magnetic susceptibility chi(T) data shows a broad maximum at about 65 K, a characteristic feature of one-dimensional (1D) magnetism. The chi(T) data is fitted to the coupled, S = 1/2 Heisenberg antiferromagnetic (HAFM) uniform chain model that gives the intra-chain coupling (J/kB) between nearest neighbour Cu2+ ions as -100 K and the ratio of inter-chain to intra-chain coupling (J'/J) as about 0.07. The exchange couplings estimated from the magnetic data analysis are in good agreement with the computed values from the electronic structure calculations based on density functional theory + Hubbard U (DFT+U) approach. The combination of theoretical and experimental analysis confirms that InCuPO5 is a candidate material for weakly coupled S = 1/2 uniform chains. A detailed theoretical analysis of the electronic structure further reveals that the system is insulating with a gap of 2.4 eV and a local moment of 0.70 muB /Cu.

cond-mat.str-el↗