Anisotropic Ru3+ 4d5 magnetism in the alpha-RuCl3 honeycomb system: susceptibility, specific heat and Zero field NMR

TL;DR

This study investigates the magnetic anisotropy and complex magnetic ordering in alpha-RuCl3, revealing field-dependent suppression of magnetic phases, coexistence of ferro- and antiferromagnetic interactions, and a likely non-coplanar chiral magnetic structure.

Contribution

It provides new insights into the anisotropic magnetic interactions and the complex magnetic structure of alpha-RuCl3 using susceptibility, specific heat, and zero-field NMR measurements.

Findings

Magnetic order is suppressed by in-plane fields but remains robust out-of-plane.

Coexistence of ferro- and antiferromagnetic exchange interactions in the plane.

Evidence of a complex, possibly non-coplanar chiral magnetic structure.

Abstract

Hexagonal alpha-Ru trichloride single crystals exhibit a strong magnetic anisotropy and we show that upon applying fields up to 14 T in the honeycomb plane the successive magnetic order at T1 = 14 K and T2 = 8 K could be completely suppressed whereas in the perpendicular direction the magnetic order is robust. Furthermore the field dependence of chi(T) implies coexisting ferro- and antiferromagnetic exchange between in-plane components of Ru^3+-spins, whereas for out-of-plane components a strong antiferromagnetic exchange becomes evident. 101^Ru zero-field nuclear magnetic resonance in the ordered state evidence a complex (probably non coplanar chiral) long-range magnetic structure. The large orbital moment on Ru^3+ is found in density-functional calculations.