The magnetoresistance is the magnetic field induced change of electrical resistivity of a material. Recent studies have revealed extremely large magnetoresistance in several nonmagnetic semimetals, which has been explained on the basis of either electron-hole compensation or the Fermi surface topology, or the combination of both. Here, we present a single crystal study on MoSi2, which exhibits extremely large magnetoresistance, approaching almost 10 7 % at 2 K and 14 T magnetic field. It is found that the electron-hole compensation level in MoSi2 evolves with magnetic field, which is resulted from strong Zeeman effect, and found beneficial in boosting the large non-saturating magnetoresistance. The non-trivial Berry phase in the de Haas-van Alphen oscillations and the moderate suppression of backward scattering of the charge carriers lend support for the topological nature of this semimetal. The ultra-large carrier mobility of the topologically protected charge carriers reinforces the magnetoresistance of MoSi2 to an unprecedented large value.

We present a study of critical current density estimated through dc magnetization measurements in the superconducting alloys Ti60V40 and Ti70V30. The magnetization is irreversible below the irreversibility field (BIrr), which is different from the upper critical field for the alloys. Additionally, the alloys are found to exhibit a peak effect in magnetization below the upper critical field. The critical current densities of the alloys estimated from the magnetization results decrease strongly with increasing magnetic field. The pinning force density follows a universal scaling relation with respect to the magnetic field divided by the BIrr. The field dependence of the pinning force density is analyzed in terms of the size of the grains of the main β phase, the possible presence of dislocation arrays within the grains of the main phase, the presence of additional metallurgical phases, and the configuration of the grain boundaries in the system. The temperature dependence of critical current density is also analyzed within the framework of existing theories.

We report experimental studies of the temperature and magnetic field dependence of resistivity and dc magnetic susceptibility and the temperature dependence of zero field heat capacity in a Ti 0.6 V 0.4 alloy. The temperature dependence of the normal state dc magnetic susceptibility in this Ti 0.6 V 0.4 alloy shows T 2 lnT behavior. The temperature dependence of resistivity follows a T 2 behaviour in the range 20-50 K. On the other hand, a term T 3 lnT is needed in the expression containing the electronic and lattice heat capacities to explain the temperature dependence of heat capacity at temperatures where T 2 dependence of resistivity is observed. Such temperature dependence of dc magnetic susceptibility, resistivity and heat capacity are indications of the presence of spin-fluctuations in the system. Further experimental evidence for the spin fluctuations is obtained in the form of a negative value of T 5 term in the temperature dependence of resistivity. The influence of spin-fluctuations on the superconducting properties of Ti 0.6 V 0.4 is discussed in detail. We show from our analysis of resistivity and the susceptibility in normal and superconducting states that the spin fluctuations present in Ti 0.6 V 0.4 alloy are itinerant in nature. There is some evidence of the existence of preformed Cooper-pairs in the temperature range well above the superconducting transition temperature. Our study indicates that the interesting correlations between spin-fluctuations and superconductivity may actually be quite widespread amongst the superconducting materials, and not necessarily be confined only to certain classes of exotic compounds.Spin-fluctuations in Ti 0.6 V 0.4

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Motivated by the report of superconductivity in RTiSb (R  =  La and Ce) and possibly NdTiSb at  ∼4 K, we grew single crystals of LaTiSb and CeTiSb by the high-temperature solution method using Sn as a flux. While in both compounds we observed a superconducting transition at 3.7 K for resistivity and low-field magnetization, our data conclusively show that it arose from residual Sn flux present in the single crystals. In particular, the heat capacity data do not present any of the anomalies expected from a bulk superconducting transition. The anisotropic magnetic properties of CeTiSb, crystallizing in a hexagonal P6/mcm structure, were studied in detail. We find that the Ce ions in CeTiSb form a Kondo lattice and exhibited antiferromagnetic ordering at 5.5 K with a reduced moment and a moderately normalized Sommerfeld coefficient of 598 mJ/mol K. The characteristic single-ion Kondo energy scale was found to be  ∼8 K. The magnetization data were subjected to a crystal electric field (CEF) analysis. The experimentally observed Schottky peak in the 4f-electron heat capacity of CeTiSb was reproduced fairly well by the energy levels derived from the CEF analysis.

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We report an experimental study on the high-field paramagnetic Meissner effect (HFPME) performed by measuring both the temperature and time dependence of magnetization in the two compositions of superconducting Ti–V alloys where certain secondary phases are non-superconducting, and thereby act as efficient pinning centres for the flux lines. While spatially non-uniform flux density driven by flux line pinning at these secondary phases is the necessary condition for the observation of the HFPME, our study indicates that the flux creep effect plays a supplementary role to reinforce the HFPME. It is found that in the temperature and magnetic field regime of the HFPME, the field-cooled magnetization of these samples relaxes monotonically towards a more positive value with elapsed time. We comment on how this paramagnetic relaxation behaviour of the field-cooled magnetization is correlated with the unusual thermo-magnetic responses related to the HFPME.

We have grown a single crystal of HoAl2Ge2, which crystallizes in the hexagonal CaAl2Si2 type structure with Ho ions in the trigonal coordination in the ab plane. The data obtained from the bulk measurement techniques of magnetization, heat capacity and transport reveal that HoAl2Ge2 orders antiferromagnetically at TN ∼6.5 K. The susceptibility below TN and isothermal magnetization at 2 K indicate the ab plane as the easy plane of magnetization. Heat capacity data reveal a prominent Schottky anomaly with a broad peak centered around 25 K, suggesting a relatively low crystal electric field (CEF) splitting. The electrical resistivity reveals the occurrence of a superzone gap below TN. The point charge model of the CEF is applied to the magnetization and the heat capacity data. While a good fit to the paramagnetic susceptibility is obtained, the CEF parameters do not provide a satisfactory fit to the isothermal magnetization at 2 K and the Schottky anomaly.