The results of our NMR, EPR and magnetic susceptibility measurements in the paramagnetic state of TlMnCl₃ are reported here. The NMR paramagnetic shift of thallium is found to be small but positive. Mn²⁺ EPR line is exchange narrowed. The susceptibility measurements indicate an antiferromagnetic transition. The heat of crystallographic phase transition ΔH, in TlMnCl₃ has been measured using differential scanning calorimetry. The crystallographic phase transition appears to be first order and ΔH is unusually low viz. 10 cal mole⁻¹. In the case of KMnF₃ Δ_H, which is reported here for the first time, is determined to be 2 cal mole⁻¹.

Nuclear quadrupole resonance (NQR) of²⁰⁹Bi has been studied in Bi₄ (GeO₄)₃ and Bi₄ (SiO₄)₃ using a wide band coherence-controlled superregenerative oscillator-detector. All the four allowed (ΔM_I=±1) transitions are observed. In both cases the electric field gradient (EFG) tensor is axially symmetric (η=0.0). The quadrupole coupling constante²qQ is measured to be 490.8±1 MHz and 470.4±1 MHz respectively. It is pointed out that the purely ionic model is inadequate to understand these results. With the available experimental accuracy and the strength of the applied electric field (∼ 6 KV/cm), no field-induced effects on the NQR spectrum could be observed in the case of Bi₄ (SiO₄)₃.

The pulse programmer generates highly stable pulses and is capable of producing various scheme of pulses (i.e. a given specific number of pulses with independently variable widths and separations) employed in pulsednmr spectroscopy. The construction and working of the programmer is described with reference to the two most commonly used schemes, namely, a two-pulse sequence and the Carr-Purcell sequence.

Effects of chemical substitution in CeRu₂Si₂, a well-studied heavy fermion system and YbPd₂Si₂ have been investigated through magnetic susceptibility and x-ray diffraction in the systems CeRu_xSi₂, CeRu_2−xOs_xSi₂, CeRu₂Si_2−xGe_x and YbPd₂Si_2−xGe_x. Replacing silicon by germanium generates normal chemical pressure effect, namely, Ce and Yb atoms in CeRu₂Si₂ and YbPd₂Si₂ became more and less magnetic respectively. With increasing Ge concentration, CeRu₂Si_2−xGe_x exhibits larger susceptibility at low temperature, goes to an antiferromagnetic state and finally becomes ferromagnetic. In YbPd₂Si_2−xGe_x, increasing Ge concentration drives Yb atoms to more divalent state. Electronic effects are more pronounced in CeRu_2−xOs_xSi₂ though CeRu₂Si₂ and CeOs₂Si₂ have very nearly the same lattice parameters. It is conjectured that CeRu₂Si_2−xGe_x may be the first Ce-based heavy fermion having a magnetic ground state.

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.

Coexistence of superconductivity and magnetic order has been one of the exciting aspects of the quaternary borocarbide superconductors, So far, RNi₂B₂C (R=Tm, Er, Ho and Dy) are the only known magnetic superconductors in this family. Here, we present our resistivity, magnetization and heat capacity studies on NdPt₂B₂C (nominal composition, NdPt_1.5Au_0.6B₂C and NdPt_2.1B_2.4C_1.2). We find superconductivity in both samples with T_c,onset ∼ 3 K. Bulk magnetic order is found to occur below 1.7 K. We suggest that NdPt₂B₂C is a possible magnetic superconductor.

The layered manganite Nd_2−2xSr_1+2xMn₂O₇, with x varying between 0 and 0.5, has been synthesized using solid-state reaction method. We have found that Nd_2−2xSr_1+2xMn₂O₇ do not form the single-phase layered compound with A₃B₂O₇ structure. Instead, mixtures of various phases, such as, orthorhombic perovskite, i.e., Nd_1−zSr_zMnO₃, layered manganite and unreacted starting compounds, have been obtained. Except for x=0.4, which is found to be an antiferromagnetic insulator, all other x values yielded metal-insulator transition and ferromagnetic ordering.