Possible Magnetic Structure with a Tilted Helical Plane in SmBe13 Probed by 9Be-NMR Study

TL;DR

This study uses 9Be-NMR to propose a tilted helical magnetic structure in SmBe13, revealing a complex magnetic order influenced by multiple interactions.

Contribution

It introduces a microscopic NMR-based analysis suggesting a novel tilted helical magnetic structure in SmBe13, expanding understanding of magnetic ordering in RBe13 compounds.

Findings

Spectral broadening depends on magnetic field direction.

Proposed helical structure with a tilted basal plane.

Balance among exchange, dipole, and anisotropy interactions influences structure.

Abstract

9Be-NMR measurements were performed using single crystalline SmBe13 in order to investigate a magnetic structure of a low-temperature ordering state microscopically. We observed a spectral broadening in the ordered state, and the broadened spectral shape depends on the magnetic field directions. By comparing the experimentally obtained and simulated NMR spectra for magnetic fields along the cubic [001] and [011] directions, we argue a helical structure with a basal plane tilted from the (001) plane in low-field ordering region under the assumption of a helical with a propagation vector of (0, 0, 1/3) found in other RBe13 compounds (R = rare earths). Such a tilted helical structure is explained by a combination of an ellipse helical in the (001) plane and a longitudinal magnetic density wave along the [001] direction. Considering a magnetic easy axis parallel to [001] revealed by the magnetization measurements, the peculiar helical structure in SmBe13 may be built on delicate balance among exchange interactions, dipole-dipole interaction, and single-ion magnetic anisotropy due to the crystalline electric field.