Intertwined magnetic sublattices in the double perovskite compound LaSrNiReO6

We report a muon spin rotation (mu+SR) study of the magnetic properties of the double perovskite compound LaSrNiReO6. Using the unique length and time scales of the mu+SR technique, we successfully clarify the magnetic ground state of LaSrNiReO6, which was previously deemed as a spin glass state. Instead, our mu+SR results point toward a long-range dynamically ordered ground state below T-C = 23 K, for which a static limit is foreseen at T = 0. Furthermore, between 23 K < T <= 300 K, three different magnetic phases are identified: a dense (23 K < T < 75 K), a dilute (75 K <= T <= 250 K), and a paramagnetic (T > 250 K) state. Our results reveal how two separate yet intertwined magnetic lattices interact within the unique double perovskite structure and the importance of using complementary experimental techniques to obtain a complete understanding of the microscopic magnetic properties of complex materials