Field-induced oscillation of magnetization blocking in holmium metallacrown magnet

TL;DR

This study reveals that the magnetization blocking barrier in holmium metallacrown SMMs oscillates with an external magnetic field due to switching relaxation mechanisms involving hyperfine interactions, enabling control over magnetization dynamics.

Contribution

It uncovers the field-dependent oscillation of the magnetization blocking barrier driven by hyperfine interactions in holmium SMMs, providing new insights into relaxation mechanisms and magnetic control.

Findings

Magnetization blocking barrier oscillates with external magnetic field.

Relaxation mechanisms switch between quantum tunneling and Orbach-like processes.

Magnetization dynamics can be manipulated via hyperfine interaction.

Abstract

Single-molecule magnets (SMMs) are promising elements for quantum informatics. In the presence of strong magnetic anisotropy, they exhibit magnetization blocking - a magnetic memory effect at the level of a single molecule. Recent studies have shown that the SMM performance scales with the height of magnetization blocking barrier. By employing molecular engineering this can be significantly modified, remaining independent from other external factors such as magnetic field. Taking advantage of hyperfine coupling of electronic and nuclear spins further enhances their functionality, however, a poor understanding of relaxation mechanisms in such SMMs limits the exploitation of nuclear-spin molecular qubits. Here we report the opening discovery of field-dependent oscillation of the magnetization blocking barrier in a new holmium metallacrown magnet driven by the switch of relaxation mechanisms involving hyperfine interaction. Single-crystal magnetic hysteresis measurements combined with first-principles calculations reveal an activated temperature dependence of magnetic relaxation dominated either by incoherent quantum tunneling of magnetization at anti-crossing points of exchange-hyperfine states or by Orbach-like processes at crossing points. We demonstrate that these relaxation mechanisms can be consecutively switched on and off by increasing the external field, which paves a way for manipulating the magnetization dynamics of SMMs using hyperfine interaction.