Phase separation and suppression of critical dynamics at quantum phase transitions of MnSi and (Sr1−xCax)RuO3 Academic Article uri icon

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  • Quantum phase transitions (QPTs) have been studied extensively in correlated electron systems. Characterization of magnetism at QPTs has, however, been limited by the volume-integrated feature of neutron and magnetization measurements and by pressure uncertainties in NMR studies using powderized specimens. Overcoming these limitations, we performed muon spin relaxation ($\mu$SR) measurements which have a unique sensitivity to volume fractions of magnetically ordered and paramagnetic regions, and studied QPTs from itinerant heli/ferro magnet to paramagnet in MnSi (single-crystal; varying pressure) and (Sr$_{1-x}$Ca$_{x}$)RuO$_{3}$ (ceramic specimens; varying $x$). Our results provide the first clear evidence that both cases are associated with spontaneous phase separation and suppression of dynamic critical behavior, revealed a slow but dynamic character of the ``partial order'' diffuse spin correlations in MnSi above the critical pressure, and, combined with other known results in heavy-fermion and cuprate systems, suggest a possibility that a majority of QPTs involve first-order transitions and/or phase separation.


  • Uemura, YJ
  • Goko, T
  • Gat-Malureanu, IM
  • Carlo, JP
  • Russo, PL
  • Savici, AT
  • Aczel, A
  • MacDougall, GJ
  • Rodriguez, JA
  • Luke, Graeme
  • Dunsiger, SR
  • McCollam, A
  • Arai, J
  • Pfleiderer, Ch
  • Böni, P
  • Yoshimura, K
  • Baggio-Saitovitch, E
  • Fontes, MB
  • Larrea, J
  • Sushko, YV
  • Sereni, J

publication date

  • January 2007