Point Contact Andreev Reflection Spin Spectroscopy in MnSi Single Crystals

ORAL

Abstract

We have carried out a detailed investigation of magnetic and spin transport properties of MnSi, an itinerant helimagnet with the weak Dzyaloshinski-Moria interaction. MnSi single crystals were grown in the form of a rod by the floating zone technique and we used the center of the rod which is clean and free from any impurities for all our measurements. Magnetization measurements suggest the critical temperature, T$_{c}$ of $\sim $ 29 K with the saturation magnetic moment of $\sim $ 0.4$\mu _{B}$/Mn at 2 K. A T$^{2}$ -- dependence of the resistance is observed near T$_{c}$, indicating that the transport is governed by spin fluctuations with a residual resistivity $\sim $ 20 $\mu \Omega $.cm. We used the point contact Andreev reflection (PCAR) technique with electrochemically etched superconducting niobium tips to observe the effects of spin polarization in a variable magnetic field as the magnetic structure of MnSi gradually transformed from helical - to conical - to weakly ferromagnetic.

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Authors

  • Pushkal Thapa

    • Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201

  • Raghava Panguluri

    • Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201

  • F. Carbone

    • D\'epartement de Physique de la Mati\`ere Condens\'e, Universit\'e de Gen\`eve, CH-1211 Gen\`eve 4, Switzerland

  • D. van der Marel

    • D\'epartement de Physique de la Mati\`ere Condens\'e, Universit\'e de Gen\`eve, CH-1211 Gen\`eve 4, Switzerland

  • A.A. Nugroho

    • Materials Science Centre, University of Groningen, 9747 AG Groningen, The Netherlands and Jurusan Fisika, Institut Teknologi Bandung, Indonesia

  • B. Nadgorny

    • Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201