Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

Competing magnetic interactions, frustration-driven quantum fluctuations, and spin correlations offer an ideal route for the experimental realization of emergent quantum phenomena with exotic quasiparticle excitations in three-dimensional frustrated magnets. In this context, trillium lattice, wherein magnetic ions decorate a three-dimensional chiral network of corner-shared equilateral triangular motifs, provides a viable ground. Herein, we present the crystal structure, dc and ac magnetic susceptibilities, specific heat, electron spin-resonance (ESR), muon spin-relaxation (μSR) results on the polycrystalline samples of K₂CrTi(PO₄)₃ wherein the Cr³⁺ ions form a two-coupled trillium lattice. The Curie-Weiss fit of the magnetic susceptibility data above 100 K yields a Curie-Weiss temperature θ_CW = −23 K, which indicates the presence of dominant antiferromagnetic interactions between S = 3/2 moments of Cr³⁺ ions. For temperatures below 40 K, the Curie-Weiss temperature is reduced to θCW = −3.5 K, indicative of the appearance of subdominant ferromagnetic interactions. The specific heat measurements reveal the occurrence of two consecutive phase transitions, at temperatures T_L = 4.3 K and T_H = 8 K, corresponding to two different magnetic phases. Additionally, it unveils the existence of short-range spin correlations above the ordering temperature T_H. The power-law behavior of ESR linewidth suggests the persistence of short-range spin correlations over a relatively wide critical region (T – T_H)/T_H > 0.25 in agreement with the specific heat results. The μSR results provide concrete evidence of two different phases corresponding to two transitions, coupled with the critical slowing down of spin fluctuations above T_L and persistent spin dynamics below T_L, consistent with the thermodynamic results. Moreover, the μSR results reveal the coexistence of static and dynamic local magnetic fields below T_L, signifying the presence of complex magnetic phases owing to the entwining of spin correlations and competing magnetic interactions in this three-dimensional frustrated magnet.