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MA: Fachverband Magnetismus

MA 62: Disodered Magnetic Materials

MA 62.7: Vortrag

Freitag, 20. März 2020, 11:00–11:15, HSZ 401

Local short-scale correlations and the origin of pseudo-diamagnetism — •Malvika Tripathi¹, T. Chatterji², H. E. Fischer², R. J. Choudhary¹, and D. M. Phase¹ — ¹UGC-DAE Consortium for Scientific Research,Indore-452001, India — ²Institut Laue-Langevin, 38042 GRENOBLE Cedex, France

Here we describe why the antiferromagnetically ordered GdCrO₃ behave in a diamagnetic way under certain conditions, by monitoring the evolution of the microscopic global and local magnetic phases. High energy neutron diffraction reveals that magnetic ordering comprises three distinct magnetic phases at different temperatures: G_x^Cr,A_y^Cr,F_z^Cr below Néel temperature = 171 K; (F_x^Cr, C_y^Cr, G_z^Cr)•( F_x^Gd,C_y^Gd) below 7 K and an intermediate phase for 7 K ≤ T ≤ 20 K in the vicinity of spin-reorientation phase transition. Although, bulk magnetometry reveals a huge negative magnetization (NM) in the terms of both magnitude and temperature range; the long-range magnetic structure and derived ordered moments remain silent about any signature of NM. Real-space analysis of the total scattering suggests significant magnetic correlations extending up to ∼ 9 Å. 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 exchange interactions with values J₁ = 2.3 K, J₂ = -1.66 K and J₃ = 2.19 K in presence of internal field, governs the observance of NM in GdCrO₃.