Weak ferromagnetic order breaking the threefold rotational symmetry of the underlying kagome lattice in CdCu3(OH)6(NO3)2·H2O

Ryutaro Okuma, Takeshi Yajima, Daisuke Nishio-Hamane, Tsuyoshi Okubo, Zenji Hiroi
2017 Physical review B  
Novel magnetic phases are expected to occur in highly frustrated spin systems. Here we study the structurally perfect kagomé antiferromagnet CdCu_3(OH)_6(NO_3)_2·H_2O by magnetization, magnetic torque, and heat capacity measurements using single crystals.An antiferromagnetic order accompanied by a small spontaneous magnetization that surprisingly is confined in the kagomé plane sets in at T_N≈4 K, well below the nearest-neighbor exchange interaction J / k_B = 45 K.This suggests that a unique q
more » ... 0 type 120^∘ spin structure with "negative" (downward) vector chirality, which breaks the underlying threefold rotational symmetry of the kagomé lattice and thus allows a spin canting within the plane, is exceptionally realized in this compound rather than a common one with "positive" (upward) vector chirality. The origin is discussed in terms of the Dzyaloshinskii-Moriya interaction.
doi:10.1103/physrevb.95.094427 fatcat:aiswmkyfozajvmsxvnfnbomxzm