1. High-moment and Exchange coupled magnetic nanostructures 

In this activity magnetic nanostructures that consist of two or more different constituents which can be of ferromagnetic (Co, Fe, FeCo alloy), antiferromagnetic (CoO, Mn) , ferrimagnetic (spinel ferrites) or spin-glass like phases with an extra unidirectional anisotropy along the interface of the magnetic materials are investigated. These nanostructures can combine very small size of their constituents  and  enhanced macroscopic magnetic properties as such they find a variety of technological applications as sensors, biosensors, microwave devices, magnetic recording devices. Our calculations include simulations in an atomic scale for single nanoparticles and a mesoscopic scaling approach developed in our group for the study of assemblies of nanoparticles.

Selected Publications

• Topochemical reduction of FeCo-oxide to FeCo-alloy nanosystems into a SiO2 matrix, Physical Chemistry Chemical Physics 27 (2025) 9504-9510
• Engineering hard ferrite composites by combining nanostructuring and Al3+ Substitution: From nano to dense bulk magnets, Acta Materialia 282 (2025) 120491
• Interplay between inter- and intra-particle interactions in bi-magnetic core/shell nanoparticles, Nanoscale Advances 3 (2021) 6912-6924
• Monte Carlo study of the superspin glass behavior of interacting ultrasmall ferrimagnetic nanoparticles,  Physical Review B 97 (2018) 094413
• Robust Ferromagnetism of Chromium Nanoparticles Formed in Superfluid Helium, Adv. Mater. 29 (2017) 1604277
• Robust antiferromagnetic coupling in hard-soft bi-magnetic core/shell nanoparticles, Nat. Comm. 4 (2013) 2960

2. Diluted Magnetic Semiconductor Nanostructures (random ferromagnets Ga_1-x Mn_x N, Cd_1-xMn_xTe)

The presence of ferromagnetic interactions without band carriers, together with a sizable spin splitting of the excitonic states makes the Ga_1−xMn_xN and Cd_1−xMn_xTe  systems suitable for magneto-optical devices, such as optical isolators, circumventing the destructive effect of antiferromagnetic interactions specific to II-VI Mn-based dilute magnetic semiconductors. We have employed numerical simulations to study the microscopic mechanisms accounting for the observed alterations of their critical temperatures and hysteresis.

Selected Publications

• Phase diagram and critical behavior of the random ferromagnet Ga_1 -xMn_xN, Phys. Rev. B 88 (R) (2013) 081201

• Origin of low-temperature magnetic ordering in Ga _1-xMn_xN, Phys. Rev. B 85 (2012 ) 205204
• Monte Carlo simulations of ferromagnetism in p-Cd_1-xMn_xTe quantum wells, Phys. Rev. Lett. 94 (2005) 127201

 

3. Binary nanoparticle composites

Nanoparticle composite systems are disordered mixtures pursuing a combination of properties to optimize a given figure of merit. Lately, the idea is epitomized by the exchange coupling strategy between magnetically soft and hard nanograins (with high saturation magnetization and large coercivity, respectively) to maximize the energy product of novel permanent magnets. We have studied the collective behaviour of binary nanoparticle composites since understanding the collective versus individual behavior of dense and diluted systems of nanoparticles becomes crucial to optimize their applications.  

Selected Publications

• Non-exchange bias hysteresis loop shifts in dense composites of soft-hard magnetic nanoparticles: New possibilities for simple reference layers in magnetic devices, Advanced Composites and Hybrid Materials 7 (2024) 182

• Bad neighbour, good neighbour: how magnetic dipole interactions between soft and hard ferrimagnetic nanoparticles affect macroscopic magnetic properties in ferrofluids, Nanoscale 12 (2020) 11222-11231

• Simultaneous Individual and Dipolar Collective Properties in Binary Assemblies of Magnetic Nanoparticles, Chem. Mater. 32 (2020) 969–981