Role Of Local Short-Scale Correlations In The Mechanism Of Negative Magnetization

We elaborate here why the antiferromagnetically ordered GdCrO3 responds in a diamagnetic way under certain conditions by monitoring the evolution of the microscopic global and local magnetic phases. Using high-energy (similar to 0.3 eV) neutrons, the magnetic ordering is shown to adopt three distinct magnetic phases at different temperatures: G(x)(Cr), A(y)(Cr), F-z(Cr) below Neel temperature (171 K); (F-x(Cr), C-y(Cr), (Cr)(Gz)) . (F-x(Gd), C-y(Gd)) below 7 K; and an intermediate phase for 7 K << T << 20 K in the vicinity of the spin-reorientation phase transition. Although bulk magnetometry reveals a huge negative magnetization (NM) in terms of both magnitude and temperature range [M-max (18 K) similar to 35M(+max) (161 K), Delta T similar to 110 K in the presence of mu(0) H = 0.01 T], the long-range magnetic structure and derived ordered moments are unable to explain the NM. Real-space analysis of the total (Bragg's + diffuse) scattering reveals significant magnetic correlations extending up to similar to 9 angstrom. Accounting for these short-range correlations with a spin model reveals spin frustration in the S = 3 ground state, comprising competing first-, second-, and third next nearest neighboring interactions with values J(1) = 2.3 K, J(2) = -1.66 K and J(3) = 2.19 K in the presence of internal field, governs the observance of NM in GdCrO3.