Spin dynamics in the staircase kagome lattice compound PbCu3TeO7

Spin dynamics of the staircase kagome lattice PbCu3TeO7 was investigated by static magnetic susceptibility χ(T), high-field magnetization M(H), and muon spin rotation/relaxation (μSR) measurements. χ(T) displays a sub-Curie power-law behavior χ(T)∼T-α with changing exponent from α=0.5 to 0.3 crossing T∗=150 K. We identify a spin-flop transition at μ0H=8.5 T and another field-induced anomaly at μ0H∗=30 T in M(H). Our μSR results unveil that the magnetically inequivalent Cu(1) and Cu(2) spins develop site-specific magnetic structures through the successive magnetic transitions at TN1=36 K, TN2=25 K, and TN3=17 K. The magnetic anomalies of PbCu3TeO7 suggest that the Cu(1) and Cu(2) subsystems feature a largely distinct magnetism due to the presence of a dozen competing exchange interactions having largely different energy scales and thus the magnetism of PbCu3TeO7 is far more complex than the staircase kagome lattice.