Basics of Magnetism in Ce Systems

• Small radius --> strongly localized Moment
• Large S-L coupling: E_so ~ 250meV ==> Hund's rule for J is important
• Lowest multiplet is J=5/2 (L=-3, S=1/2)

• J multiplet is split by Crystal Electric Field (CEF)
• typically: J is split into 3 doublets
  • Kramers doublet ==> only doublet d.o.f. ==> dipolar ordering
• cubic: J is split into doublet + quartet
  • quadrupolar ordering

• CeB6 and Ce3Pd20Si6
• quadrupolar ordering at T_Q
• Dipolar ordering at T_N < T_Q

• T_Q often increases strongly with field (see e.g. [1])

  Linked Notes:
  CeRh2As2 talk by Christoph Geibel

  Tags:
  Interesting Materials

  References:
  [1] J. Custers et al., Nature Materials 11 189 (2012).