Regensburg 2025 – scientific programme
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MA: Fachverband Magnetismus
MA 40: Frustrated Magnets II
MA 40.6: Talk
Thursday, March 20, 2025, 16:15–16:30, H20
Single crystal growth and anisotropic magnetic properties of honeycomb quantum antiferromagnets: Ba2A(PO4)2 (A = Ni, Co, Mn) — •Aditi Agrawal1, Koushik Chakraborty1, Isha Isha1, M. Isobe2, and Arvind Kumar Yogi1 — 1UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore-452001, India — 2Max-Planck-Institut f\"{u}r Festk\"{o}rperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany
The magnetic framework (monoclinic-lattice) of the title compounds are composed of the honeycomb-lattice. We present a study of high-quality Ba2A(PO4)2 (A = Ni, Co, Mn) optically floating zone grown single crystals. Sharp anomalies were found in the thermodynamic measurements. The anomalies corresponding to the long-range-ordering (LRO) for all three single-crystals of honeycomb family were evident just below 5 K, reveals a long-range antiferromagnetic order in these single-crystalline samples. The dc-susceptibilities for in-plane and out-of-plane magnetic fields are strongly anisotropic. Our Curie-Weiss analysis for Ni, Co, and Mn suggest strong orbital magnetism but it was found significant for Co2+ case, as it is known due to its Kramers' degeneracy nature. Further, on application of external magnetic field, all compound shows spin-flop transition at moderate field. However, Ba2Co(PO4)2 is interestingly driven to another ordered phase due to the field-induced transition via a field tuned quantum critical point which is expected close to the critical field of Bc ~ 6.5 T, as evident from our phase boundaries analysis on in B-T plane.
Keywords: Quantum Magnets; Antiferromagnetism; Honeycomb-lattice; NMR; Frustrated lattice