We have investigated the magnetic properties of highly anisotropic layered ferromagnetic semiconductor CrI3 under hydrostatic pressure with magnetic field along the easy-axis of magnetization. At ambient pressure, CrI3 undergoes a second-order paramagnetic to ferromagnetic phase transition at TC =60.4 K. TC is found to increase sublinearly from 60.4 to 64.9 K as pressure increases from 0 to 1.0 GPa. With the increase in pressure, the transition becomes sharper while magnetization at low-field decreases monotonically due to the decrease in magnetocrystalline anisotropy. The weak low-field anomaly at around 48 K, resulting from the two-step magnetic ordering, also shifts toward higher temperature with increasing pressure. The observed increase in TC and the decrease in magnetization could originate from change in coupling between the layers and Cr-I-Cr bond angle with pressure.

The impact of hydrostatic pressure (P) up to 1 GPa on Tc, Jc and the nature of the pinning mechanism in FexNbSe2 single crystals have been investigated within the framework of the collective theory. We found that the pressure can induce a transition from the regime where pinning is controlled by spatial variation in the critical transition temperature (δTc) to the regime controlled by spatial variation in the mean free path (δℓ). Furthermore, Tc and low field Jc are slightly induced, although the Jc drops more rapidly at high fields than at ambient P. The pressure effect enhances the anisotropy and reduces the coherence length, resulting in weak interaction of the vortex cores with the pinning centers. Moreover, the P can induce the density of states, which, in turn, leads to enhance in Tc with increasing P. P enhances the Tc with the rates of dTc/dP of 0.86, 1.35 and 1.47 K/GPa for FexNbSe2, respectively. The magnetization data are used to establish a vortex phase diagram. The nature of the vortices has been determined from the scaling behaviour of the pinning force density extracted from the Jc–H isotherms and demonstrates the point pinning mechanism.

Sc5Rh6Sn18 with a cage-type quasiskutterudite crystal lattice and type II superconductivity, with superconducting transition temperature Tc = 4.99 K, was investigated under hydrostatic high-pressure (HP) using electrical transport, synchrotron X-ray diffraction (XRD) and Raman spectroscopy. Our data show that HP enhance the metallic nature and Tc of the system. Tc is found to show a continuous increase reaching to 5.24 K at 2.5 GPa. Athough the system is metallic in nature, Raman spectroscopy investigations at ambient pressure revealed the presence of three weak modes at 165.97, 219.86 and 230.35 cm-1, mostly related to the rattling atom Sc. The HP-XRD data revealed that the cage structure was stable without any structural phase transition up to ~7 GPa. The lattice parameters and volume exhibited a smooth decrease without any anomalies as a function of pressure in this pressure range. In particular, a second order Birch-Murnaghan equation of state can describe the pressure dependence of the unit cell volume well, yielding a bulk modulus of ~ 97 GPa. HP Raman investigations revealed a linear shift of all the three Raman modes to higher wavenumbers with increasing pressure up to ~8 GPa. As the pressure enhances the bond overlap, thus inducing more electronic charges into the system, HP-XRD and Raman results may indciate the possibility of obtaining higher Tc with increasing pressures in this pressure range.

We report here on the complex magnetic structure and magnetocapacitance in NiF 2 , a non-oxide multifunctional system. It undergoes an anti-ferromagnetic transition near 68.5 K, superimposed with canted Ni spin driven weak ferromagnetic ordering, followed by a metastable ferromagnetic phase at or below 10 K. Our density functional calculations account for the complex magnetic structure of NiF 2 deduced from the temperature and the field dependent measurements. Near room temperature, NiF 2 exhibits a relatively large dielectric response reaching >10 3 with a low dielectric loss of <0.5 at frequencies >20 Hz. This is attributed to the intrinsic grain contribution in contrast to the grain boundary contribution in most of the known dielectric materials. The response time is 10 μs or more at 280 K. The activation energy for such temperature dependent relaxation is ~500 meV and is the main source for grain contribution. Further, a large negative magneto capacitance >90% is noticed in 1 T magnetic field. We propose that our findings provide a new non-oxide multifunctional NiF 2 , useful for dielectric applications.

We report high pressure structural studies (52 GPa) at room temperature combined with magnetic [(M(T):1GPa] and electrical resistivity [(ρ(T):0-21GPa)] measurements down to 2K on Fe0.99Ni0.01Se0.5Te0.5 superconductor using designer diamond anvils (D-DAC) pressure cell. The M(T) data shows huge enhancement of superconducting transition temperature (Tc) from 8.62 to 14.8 K (1 GPa) and ρ(T) reveals maximum enhancement of Tc ~ 30.5 K at 3 GPa (dTc/dP= ~ 7.19 K/GPa) followed by moderate decrease of Tc up to 19 K at 7.5 GPa, further increasing pressure Tc gets vanished at 10.6 GPa. The reduction of Tc due to the occurrence of structural transition that is likely associated with possible reduction of charge carriers in the density of states in Fermi surface. The high pressure XRD measurements shows tetragonal phase exists up to 7 GPa, followed by mixed-phase which is visible between 7.5 GPa to 14.5 GPa. The structural transformation occurs at 15 GPa from tetragonal (P4/nmm) to NiAs -type hexagonal phase (P63/mmc) and it is stable up to 52 GPa were confirmed from the equation of state (EOS) and it can be correlated with variation of Tc under pressure for Fe0.99Ni0.01Se0.5Te0.5 chalcogenide superconductors.