Metastable 1T-RhO₂ with a Triangular Lattice: A Possible Quantum Spin Liquid Candidate.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Magnetism

Background:

• Layered van der Waals (vdW) magnets are crucial for low-dimensional magnetism and device applications.
• Most existing vdW magnets utilize 3d transition metals.
• Exploring 4d and 5d transition metal systems is vital for discovering exotic magnetic phenomena driven by electronic correlations and spin-orbit coupling (SOC).

Purpose of the Study:

• To synthesize and characterize a novel metastable layered vdW crystal containing a 4d transition metal.
• To investigate the magnetic and electronic properties of the synthesized material.
• To explore its potential as a quantum spin liquid (QSL) candidate.

Main Methods:

• Topochemical reaction synthesis of 1T-RhO2 from Cs0.5RhO2 single crystals.
• Electrical transport measurements to determine conductivity.
• Magnetic susceptibility and alternating current susceptibility to probe magnetic order.
• Raman spectroscopy to identify fermionic excitations.
• Angle-resolved photoemission spectroscopy (ARPES) and hybrid functional calculations to determine electronic band structure.

Main Results:

• Successful synthesis of metastable 1T-RhO2, a layered vdW triangular lattice crystal.
• 1T-RhO2 confirmed as an electrical insulator with a band gap of approximately 1.0 eV.
• Absence of long-range magnetic order or spin glass behavior down to 2 K.
• Observation of fermionic excitations potentially indicative of fractionalized Majorana fermions.
• Identification of 1T-RhO2 as a promising quantum spin liquid (QSL) candidate.

Conclusions:

• The synthesized 1T-RhO2 represents a significant advancement in 4d transition metal vdW magnets.
• The material's properties suggest it is a potential quantum spin liquid (QSL) candidate.
• This work expands discovery pathways for QSLs in metastable materials.