Thermodynamics of the two-dimensional frustrated J1-J2 Heisenberg ferromagnet in the collinear stripe regime: Susceptibility and correlation length

We calculate the temperature dependence of the correlation length. and the uniform susceptibility chi(0) of the frustrated J(1)-J(2) square-lattice Heisenberg ferromagnet in the collinear stripe phase using the Green-function technique. The height chi(max) and the position T (chi(max)) of the maximum in the chi(0)(T) curve exhibit a characteristic dependence on the frustration parameter J(2)vertical bar|J(1)vertical bar, which is well described, for J(2) > 0.7 vertical bar J(1)vertical bar, by the relations chi(max) = a(J2 -J(2)(c))(-nu) and T (chi(max)) = b(J(2) -J(2)(c)), where J(2)(c) = 0.4 vertical bar J(1)vertical bar and. is of the order of unity. The correlation length diverges at low temperatures as xi alpha e(A/T), where A increases with growing J(2)/vertical bar J(1)vertical bar. We also compare our results with recent measurements on layered oxovanadates and find reasonable agreement. DOI: 10.1103/PhysRevB.87.054412