S. W. D'Souza

Antiferromagnetic exchange interactions in the Ni2Mn1.4In0.6ferromagnetic Heusler alloy

Magnetism in Ni-Mn-Z (Z = Ga,In,Sn,Sb) Heusler alloys has so far been predominantly attributed to Rudermann-Kittel-Kasuya-Yoshida type interactions between Mn atoms. We investigate magnetic interactions in one such alloy, Ni

Large Magnetization and Reversible Magnetocaloric Effect at the Second-Order Magnetic Transition in Heusler Materials

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Magnetic properties and magnetocaloric effect in Pt doped Ni-Mn-Ga

Mn

Chemical disorder as an engineering tool for spin polarization in Mn3Ga-based Heusler systems

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Room-temperature tetragonal non-collinear Heusler antiferromagnet Pt2MnGa

In

Resonant impurity states in chemically disordered half-Heusler Dirac semimetals

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Surface Study of Ni2MnGa(100)

and attempt to explain the origin of antiferromagnetic (AFM) interactions that coexist with ferromagnetic ones. Through the combination of x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD), we find that Ni plays an important role along with Mn in the overall magnetism. A significant hybridization that develops between Mn and Ni orbitals results in a small antiferromagnetic moment at Ni sites. The shift in the XMCD hysteresis loops in the martensitic phase suggests that antiferromagnetism results from superexchange like interactions between Mn atoms mediated by Ni.

Adaptive modulation in the Ni2Mn1.4In0.6 magnetic shape-memory Heusler alloy

In contrast to rare-earth-based materials, cheaper and more environmentally friendly candidates for cooling applications are found within the family of Ni-Mn Heusler alloys. Initial interest in these materials is focused on the first-order magnetostructural transitions. However, large hysteresis makes a magnetocaloric cycle irreversible. Alternatively, here it is shown how the Heusler family can be used to optimize reversible second-order magnetic phase transitions for magnetocaloric applications.

Modulation on Ni2MnGa(001) surface

Large magnetocaloric effect is observed in Ni1.8Pt0.2MnGa close to room temperature. The entropy change shows a crossover from positive to negative sign at the martensite transition. It is negative above 1.6 T and its magnitude increases linearly with magnetic field. An increase in the saturation magnetic moment is observed with Pt doping in Ni2MnGa. Ab initio theoretical calculations show that the increase in magnetic moment with Pt doping in Ni2MnGa is associated with increase in the Mn and Pt local moments in the ferromagnetic ground state. The Curie temperature calculated from the exchange interaction parameters is in good agreement with experiment, showing the absence of any antiferromagnetic correlation due to Pt doping.

Spin-Valve-Like Magnetoresistance in Mn2NiGa at Room Temperature

Our study highlights spin-polarization mechanisms in metals by focusing on the mobilities of conducting electrons with different spins instead of their quantities. Here, we engineer electron mobility by applying chemical disorder induced by nonstoichiometric variations. As a practical example, we discuss the scheme that establishes such variations in tetragonal