Ground State of the Easy-Axis Rare-Earth Kagom\'e Langasite Pr$_3$Ga$_5$SiO$_{14}$

Understand

We report muon spin relaxation ($\mu$SR) and $^{69,71}$Ga nuclear quadrupolar resonance (NQR) local-probe investigations of the kagom\'e compound Pr$_3$Ga$_5$SiO$_{14}$.

• Small quasi-static random internal fields develop below 40 K and persist down to our base temperature of 21 mK.
• They originate from hyperfine-enhanced $^{141}$Pr nuclear magnetism which requires a non-magnetic Pr$^{3+}$ crystal-field (CF) ground state.
• Besides, we observe a broad maximum of the relaxation rate at $\simeq 10$ K which we attribute to the population of the first excited magnetic CF level.