Investigation of ionic and anomalous magnetic behavior in CrSe₂ using ⁸Li β-NMR

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nuclear Physics

Background:

• 1T-CrSe2 is a layered transition metal dichalcogenide with interesting electronic and magnetic properties.
• Understanding ion dynamics and site occupation in such materials is crucial for potential applications.

Purpose of the Study:

• Investigate the local magnetic environments and diffusion mechanisms of implanted 8Li ions in 1T-CrSe2 single crystals.
• Correlate the observed phenomena with the known structural and magnetic transitions of 1T-CrSe2.

Main Methods:

• Utilized beta-detected nuclear magnetic resonance (β-NMR) spectroscopy.
• Performed measurements on 8Li implanted 1T-CrSe2 single crystals over a temperature range of 4 to 300 K.

Main Results:

• Identified two distinct magnetic environments for 8Li ions, evidenced by broad, unsplit resonances.
• Observed temperature-dependent spin-lattice relaxation rates (1/T1) indicating ionic diffusion above 200 K.
• Noted a maximum in 1/T1 at the 20 K magnetic transition and an anomalous minimum between 150-200 K, near structural/magnetic transitions.

Conclusions:

• The behavior of 8Li is consistent with occupation of the van der Waals gap between CrSe2 trilayers.
• The two magnetic environments likely arise from distinct interstitial sites within the van der Waals gap.
• Further investigation is needed to fully elucidate the origins of the observed magnetic environments.