arXiv subjects

Chhayabrita Maji

Publications and source records attributed to Chhayabrita Maji.

2 recordsLinked to original sources

arXiv2017

Effect of co-existing crystal structures on magnetic properties of Ni_2Mn_(1+x)Sn_(1-x) magnetic shape memory alloy

The temperature dependent crystal structure analysis in martensitic phase of Ni_2Mn_(1+x)Sn_(1-x) (x = 0.40 and 0.44) magnetic shape memory alloy is performed using X-ray diffraction. The martensitic phase consists of 4-Layered and 14-Layered orthorhombic structure. The phase fraction of 4-layered and 14-layered orthorhombic structure change with temperature. Interestingly, the magnetic property also changes with temperature and corresponds to structural change temperature. Thus, the exchange coupling constant between original Mn and substituted Mn is calculated, which shows that the 4-layered and 14-layered orthorhombic structures have different strength of antiferromagnetic coupling. The analysis explain the origin of spin glass behavior and unusual exchange bias effect in these systems under zero-field-cooling.

cond-mat.mtrl-sci↗

arXiv2016

Driving force for martensitic transformation in Ni$_{2}$Mn$_{1+x}$Sn$_{1-x}$

The martensitic transformation in Ni$_{2}$Mn$_{1+x}$Sn$_{1-x}$ alloys has been investigated within ab-initio density functional theory. The experimental trend of a martensitic transition happening beyond $x$ = 0.36 is captured within these calculations. The microscopic considerations leading to this are traced to increased Ni-Mn hybridization which results from the Ni atom experiencing a resultant force along a lattice parameter and moving towards the Mn atoms above a critical concentration. The presence of the lone pair electrons on Sn forces the movement of Ni atoms away from Sn. While band Jahn Teller effects have been associated with this transition, we show quantitatively that atleast in this class of compounds they have a minor role.

cond-mat.mtrl-sci↗