Abstract:
The present study reports the evolution of microstructure and magnetic properties of Cu2MnAl1−xGax Heusler alloys. The L21 phase, which remained stable up to a Ga substitution of x = 0.3, transformed into mixed phases, i.e., hexagonal close packed (HCP) and complex cubic structure (CCS) on further addition of Ga. The non-monotonic increase in the lattice constant indicates that some amount of Ga retains its monovalent state. The magnetic phase showed a transition from ferromagnetic to paramagnetic state with increasing Ga concentration. The re-entrant temperature (TR) decreased from 8.2 K to 5.2 K as Ga content increased from 5 at% to 10 at%. The strength of magnetic exchange-coupling also reduced with an increase in Ga content. Gaussian process regression (GPR) was used to estimate the lattice parameter using the ionic radii and Pauling electronegativity of the constituents. The modeling approach showed high accuracy and stability, providing new insights into future alloy development.
Description:
S. S. Mishra thanks the University Grants Commission (UGC), India, for the BSR fellowship, during which period the work was completed. RMY acknowledges the United States-India Educational Foundation ( USIEF ) and Fulbright Foreign Scholarship Board (FFSB), USA, for Fulbright Nehru Academic and Professional Excellence Fellowship. The work performed at the Texas Center for Superconductivity at the University of Houston is supported by the U.S. Air Force Office of Scientific Research Grant FA9550-15-1-0236 , the T. L. L. Temple Foundation, the John J. and Rebecca Moores Endowment, and the State of Texas through the Texas Center for Superconductivity at the University of Houston. S.S.M. acknowledges Ms. Khushubo Tiwari for encouraging discussions while preparing the manuscript. A.B.P. acknowledges IUSSTF and SERB India for financial support in the form of the postdoctoral fellowship.
