Displaced hysteresis loops in zero-magnetization spin ferromagnetic alloy Sm1-xGdxAl2 (x = 0.01-0.06) & Physical Properties of β-(Ti,M)6Sn5 systems (M = Cr, Mn, Fe & Co)

Abstract 1: Sm_1-xGd_xAl_2

Isothermal magnetic hysteresis loops in polycrystalline samples of spin ferromagnetic Sm_1-xGd_xAl_2 [x = 0.01-0.06] alloys which imbibe ‘near zero magnetization characteristics’ were recorded at several temperatures below the magnetic ordering temperature (T_c~125K). The initial magnetic state was produced by pre-cooling the sample in a “high” field (7T), from the paramagnetic state, down to the desired target temperature below T_c. The loop parameters, the effective coercive field (H_c^eff) and the loop-shift along the field axis (H_exch), were followed. In compositions having magnetic compensation (x<~0.03), say at a temperature T_comp, the loop shift changes sign across ~ T_comp (i.e. passes through zero at ~ T_comp) and (H_C^eff) also shows a minimum at T_comp.  We argue that ideally, for a perfectly homogenous sample, both the H_^eff Cand the loop-shift must be exactly zero at T_comp, irrespective of the thermal and magnetic history of sample. Further, we infer that the loop-shift for the spin surplus state and its reversed orbital surplus state are opposite of each other, at least over a small temperature window at ~ T_comp. 

Abstract 2: β-Ti6Sn5

The β-Ti6Sn5 is a Pauli paramagnetic system displaying a Fermi liquid behavior, addition of magnetic impurities drives it to a ferromagnetic state. The effect of doping on the magnetic properties suggested that β-Ti6Sn5 exhibiting a ground state in close proximity to a non-magnetic and magnetic phase boundary, also, a large Wilson ratio (R_w = 1.76) of this system is an indication of correlated electron behavior.

In the present study we have to substitute Ti by other transition elements like Cr, Mn, Fe and Co (single crystalline and polycrystalline) and studied their physical properties by magnetization, resistivity and specific heat capacity measurements. The results will be discussed in the talk. Various aspects on the preparation of β-Ti6Sn5 single crystals will also be discussed as this phase becomes metastable below 790 °C.