Muon spin rotation study to investigate a possible spin liquid behaviour in 1D spin-chain compound K2PrNb5O15

The K2RENb5O15 (RE = rare earths) having tetragonal tungsten-bronze structure present interesting magnetic ground state where the RE3+ ions from 1D linear spin-chain along the c-axis. The magnetic measurements on K2PrNb5O15 have shown absence of long-range magnetic ordering in magnetic susceptibility χ(T) down to 1.8 K accompanied with a strongly reduced isothermal magnetization M(H) due to strong crystal electric field (CEF) effect. Our heat capacity measurements in zero-field as well as in applied fields find no anomaly related to a magnetic phase transition down to 130 mK, however the magnitude increases in applied fields, suggesting the presence of ferromagnetic correlations. Our inelastic neutron scattering study on K2PrNb5O15 on MARI reveals well defined CEF excitations indicating arising from localized Pr moments. Absence of magnetic ordering down to 130 mK together with strong CEF is indicative of CEF-driven spin-liquid-like feature in this compound. Further investigations using the microscopic muon spin relaxation measurements are highly required to investigate the spin-dynamics and possible spin-liquid behavior in 1D Pr-spin-chain system K2PrNb5O15. We therefore propose to carry out µSR measurements on K2PrNb5O15 using the μSR spectrometer EMU.