51 research outputs found
Skyrmion lattice and critical behavior of Fe<inf>0.6</inf>Co<inf>0.4</inf>Si: A bulk magnetization study
No full textCritical behavior, universal magnetocaloric, and magnetoresistance scaling of MnSi
No full textWe report the critical behavior of a B20 cubic compound MnSi, known by its helical, conical and skyrmion phases in low fields, in its magnetic field-induced ferromagnetic (high-field) phase by means of magnetic-entropy (magnetoresistance) methods. The evaluated critical exponents are beta = 0.25 +/- 0.02(0.19 +/- 0.04), gamma = 1.29 +/- 0.27 (1.32 +/- 0.16), and delta = 6.18 +/- 0.28 (7.79 +/- 0.52). The self-consistency of the newly adopted methods is established by comparing the thus obtained exponents with those estimated using the modified Arrott's plot method and neutron diffraction. The field controlling parameter is n similar to 0.5 and its deviation from the mean-field model exponent confirm the weak first-order and field-induced ferromagnetic behavior. A direct proportional relation between magnetic entropy and magnetoresistance infers itinerant magnetic nature. The collapse of high-field data onto the more generalized magnetic-entropy master curve confirms the field-induced first-to second-order phase transition and thereby tricritical phenomenon in MnSi
Critical exponents and universal magnetic behavior of noncentrosymmetric Fe<sub>0.6</sub>Co<sub>0.4</sub>Si
No full textSpin-flop quasi-first order phase transition and putative tricritical point in Gd3Co
No full textMagnetic nature of Gd3Co is investigated using detailed measurements of temperature and field dependent magnetization. The antiferromagnetic phase is field-instable due to prevailing ferromagnetic exchange correlations above Neel temperature T-N similar to 130 K. Below T-N, with gradually increasing magnetic fields, the compound undergoes a quasi-first order phase transition from AFM to spin-flop over region and eventually acquires ferromagnetic phase in higher fields. Further the point at which the quasi-first order transition ends and second order transition sets in is the tricritical point, T-TCP similar to 125: 6 K, H-TCP similar to 4: 4 kOe. (C) 2017 Elsevier B.V. All rights reserved
Unfolding magnetic, electrical and universal magneto-resistance scaling behavior of Ni2Mn1−xCoxIn
No full textWe uncover the magnetic, electrical transport properties and universal magneto-resistance scaling nature of cubic Ni2Mn1−xCoxIn with nominal compositions of x = 0.05 and 0.1. Positive Weiss temperature, magnetic saturation in relatively low fields, non-hysteretic and non-coercive signatures confirm soft-ferromagnetic behavior of the alloys. Formation of random ferromagnetic clusters in the paramagnetic state for x = 0.1 is noticed through Griffith’s phase signatures in inverse susceptibility. Rhodes–Wohlfarth analysis confirms the itinerant magnetic nature. These alloys exhibit metallic character with Fermi liquid behavior at low temperatures. Relatively smaller negative magneto-resistance indicates the suppression of itinerant spin fluctuations and incoherent scattering of conduction electrons. Second order magnetic phase transition is inferred from a well-scaled normalized magneto-resistance independent of magnetic field strength. Our study stimulates interest to unravel the ground state physical and magnetic properties of substituted (non-magnetic/magnetic for Mn Ni and In) soft-ferromagnetic Ni2MnIn
Pressure induced martensitic transition, magnetocaloric and magneto-transport properties in Mn-Ni-Sn Heusler alloy
No full textSem informaçãoIn this work, we report the effect of hydrostatic pressure (P) on the martensitic transition in Mn50Ni40Sn10 Heusler alloy using the magnetization and electrical resistivity measurements. Martensitic transition temperature (T-M) is found to shift significantly to higher temperatures with the application of pressure, which reflects the stabilization of the martensite phase. On the other hand, T-M shifts to lower temperatures with magnetic field, which implies the stabilization of the austenite phase. The estimated rate of change of martensitic transition temperature with pressure (dT(M)/dP) for the present alloy is similar to 4.6 K/kbar. The alloy shows a maximum negative magnetoresistance (MR) of 9.6% for P = 4 kbar at the martensitic transition. A large isothermal magnetic entropy change (Delta S-M) of 16.6 J/kg.K and a refrigerant capacity (RC) of similar to 146 J/kg are observed at TM under ambient pressure. Both quantities are found to decrease with the increase of pressure. The values of Delta S-M and adiabatic temperature change (Delta T-ad), calculated from heat capacity measurements are similar to 11.3 J/kg. K and -3.4 K respectively for 50 kOe field change. The observed pressure and field dependence results have been explained using the Clausius-Clapeyron equation. The combined effect of pressure and field on the martensitic transition is also discussed.48717Sem informaçãoSem informaçãoSem informaçãoAuthors acknowledge BRNS-DAE for the financial assistance granted through a sponsored research project. J. Sharma would like to acknowledge the SERB-DST Govt. of India for the financial assistance granted through a NPDF project. The work on pressure dependent electrical properties was conducted by NTU-HUJ-BGU Nanomaterials for Energy and Water Management Programme under the Campus for Research Excellence and Technological Enterprise (CREATE), that is supported by the National Research Foundation, Prime Minister's Office, Singapore. Author would like to acknowledge Dr. S. Shanmukharao Samatham for important discussion
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