Mar 20 – 23, 2023
Campus Garching
Europe/Berlin timezone

Ordered and disordered variants of the triangular lattice antiferromagnet Ca3NiNb2O9

Mar 21, 2023, 4:00 PM
Yards 4 - 6 (Fakultät für Maschinenwesen)

Yards 4 - 6

Fakultät für Maschinenwesen

Board: TU-236
Poster Magnetism, Superconductivity, Topological Systems, Magnetic Thin Films an other electronic phenomena Poster session TUESDAY


Ran Tang (Technical Univertsity Munich)


Single crystals of the triangular lattice antiferromagnet (TLAF) Ca$_3$NiNb$_2$O$_9$ and its non-magnetic analogue Ca$_3$MgNb$_2$O$_9$ are grown using the four-mirror optical float-zone furnace. During the growth of Ca$_3$NiNb$_2$O$_9$, the crystal boule tends to develop cracks upon cooling due to a high-temperature structural modification. Thus, depending on the growth conditions, the crystal boules contain varying amounts of high and low-temperature modifications, present in the form of mm-size grains distinguishable on the basis of their appearance: opaque, dark-green (AGO) and translucent, light-green (AGT) for the high and low-temperature modifications, respectively. Furthermore, when the as-grown, AGO specimen is subject to air annealing at 1200°C, its appearance change from opaque to translucent green, without any noticeable change of weight. Low temperature specific heat and low-field magnetization measurements carried out on the AGO and AGT samples revealed contrasting ground state properties. While AGO exhibits a spin-glass-like ground state, the AGT sample exhibit a two-step, long-range antiferromagnetic ordering of the Ni spins with transitions at $T_{\mathrm{N}_{1}}$ $=$ 4.6 K and $T_{\mathrm{N}_{2}}$ $=$ 4.2 K. Detailed structural analysis shows that AGO and AGT crystals crystallize in Pbnm (orthorhombic) and
$P12_1/c_1$ (monoclinic) space groups, respectively. The high-resolution TEM images confirms the 1:2 ordering of Ni and Nb in the AGT sample. The high-field magnetization up to 50 T in AGT reveals the presence of magnetization plateaus characteristic of TLAFs. The propagation vector in the ordered phase (2 K) is inferred to be $\vec{k} \approx (0, 1/3, 0)$ based on the magnetic neutron scattering.

Primary authors

Mr Bachir Ouladdiaf (Institut Laue-Langevin) Ms Dibyata Rout (Indian Institute of Science Education and Research) Markos Skoulatos (TUM) Ran Tang (Technical Univertsity Munich) Mr Surjeet Singh (Indian Institute of Science Education and Research)


Atsushi Miyake (The University of Tokyo) Masashi Tokunaga (The University of Tokyo) Sagar Mahapatra (Indian Institute of Science Education and Research) Yuto Kinoshita (The University of Tokyo)

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