We report here the results of our heat capacityC_p measurements on a monophasic material HoBa₂Cu₃O_7−y. ΔC_p/T_c, the jump inC_p at the superconducting transition temperature (=91 K) of the material is measured to be 31 mJ/mol-K².

ac Conductivity measurements are carried out across the metal to insulator transition in NiAl_0.7Cr_0.7Fe_0.6O₄. The low frequency data is analyzed using Summerfield scaling theory for hopping conductivity. The exponent of the scaling behavior has significantly different values in the conducting and insulating regimes. The hopping frequency and the zero frequency conductivity are found to increase with temperature, slowly in the metallic regime and rapidly in the insulating regime.