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), 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

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

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