Manipulating 4f quadrupolar pair interactions in TbB2C2 using a magnetic field

TL;DR

This study investigates how magnetic fields influence the quadrupolar interactions of 4f electrons in TbB2C2, revealing that these interactions can be controlled by external magnetic fields, with implications for understanding orbital physics.

Contribution

It demonstrates experimentally that the quadrupolar pair interaction in TbB2C2 depends on orbital orientation and can be manipulated using a magnetic field, confirming theoretical predictions.

Findings

Quadrupole moments are ordered below T_N and align ferroquadrupolarly.

Applied magnetic field causes a gradual rotation of magnetic dipole moments.

Quadrupolar interactions depend on orbital orientation and are controllable by magnetic field.

Abstract

Resonant soft x-ray Bragg diffraction at the Tb M4,5 edges and non resonant Bragg diffraction have been used to investigate orbitals in TbB2C2. The Tb 4f quadrupole moments are ordered in zero field below T_N and show a ferroquadrupolar alignment dictated by the antiferromagnetic order. With increasing applied field along [110] the Tb 4f magnetic dipole moments rotate in a gradual manner toward the field. The quadrupole moment is rigidly coupled to the magnetic moment and follows this field-induced rotation. The quadrupolar pair interaction is found to depend on the specific orientation of the orbitals as predicted theoretically and can be manipulated with an applied magnetic field.