KIAS workshop "From correlated electrons to nanoscale materials"

at Korea Institute for Advanced Study (KIAS), Seoul, Korea

• Masaki Oshikawa
  
  ISSP, University of Tokyo
  
  

  Title

  Field-induced critical phenomena in (quasi) one-dimensional spin gap systems

  Abstract

  A spin gap system in an applied magnetic field undergoes a quantum phase transition at zero temperature, when the gap is closed by the applied field. If the system is one dimensional, the quantum critical point is described by a free fermion effective theory, while the gapless phase above the critical field can be regarded as a Tomonaga-Luttinger liquid. The quantum critical phenomena associated to this field-induced transition may be among the simplest yet nontrivial examples of quantum phase transition. However, several of its physical consequences have been apparently overlooked. In this talk, I will discuss our recent findings on this topic: (i) magnetization minimum as a function of the temperature (ii) phase diagram of weakly coupled one-dimensional spin gap systems.