Magnetic and nonmagnetic impurity effect on magnetic orderings of the isosceles-triangular-lattice antiferromagnet CuMnO2

Abstract

We have investigated the magnetic and the nonmagnetic impurity substitution effects on the magnetic ordering of a frustrated isosceles-triangular-lattice antiferromagnet CuMnO2 by means of magnetic neutron diffraction measurements on Cu(Mn1−y Ga y )O2. While the magnetic wave vector of the magnetic ground state of “magnetically”-substituted Cu(Mn1−x Cu x )O2 with · = 0·04 is $$Q = \left( {\tfrac{{\bar 1}} {2}\tfrac{1} {2}0} \right)$$ , that in the “nonmagnetically”-substituted Cu(Mn1−y Ga y )O2with · =0.05, 0.15 and 0.20 is $$Q = \left( {\tfrac{{\bar 1}} {2}\tfrac{1} {2}\tfrac{1} {2}} \right)$$ , which is identical to that of pure CuMnO2. We discuss the influence of magnetic or nonmagnetic impurity substitution on the magnetic ordering of CuMnO2, by comparing the results for Cu(Mn1−y Ga y )O2with that for Cu(Mn1−x Cu x )O2.