The structure of K2Ni2(MoO4)3 consists of S=1 tetramers formed by Ni2+ ions. The magnetic susceptibility χ(T) and specific heat CP(T) data on a single crystal show a broad maximum due to the low dimensionality of the system with short-range spin correlations. A sharp peak is seen in χ(T) and CP(T) at about 1.13 K, well below the broad maximum. This is an indication of magnetic long-range order, i.e., the absence of spin gap in the ground state. Interestingly, the application of a small magnetic field (H>0.1 T) induces magnetic behavior akin to the Bose-Einstein condensation (BEC) of triplon excitations observed in some spin-gap materials. Our results demonstrate that the temperature-field (T-H) phase boundary follows a power law (T-TN) 1/α with the exponent 1/α close to 23, as predicted for the BEC scenario. The observation of BEC of triplon excitations in small H infers that K2Ni2(MoO4)3 is located in the proximity of a quantum critical point, which separates the magnetically ordered and spin-gap regions of the phase diagram. © 2017 American Physical Society.

Panchanana Khuntia

Department Of Physics

Fulltext

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IIT Madras

Physical Review B

Spin correlation, competing interactions and subtle interplay between various degrees of freedom can lead to novel quantum states in correlated electron systems. Insights into the intrinsic magnetic susceptibility and the origin of complex magnetic ordering on a microscopic scale set an attractive setting in correlated quantum matter. In this context, Nuclear Magnetic Resonance (NMR) probe offers an unprecedented approach to explore the underlying physical mechanism of correlated quantum phenomena in condensed matter physics. NMR is a site selective microscopic technique extremely sensitive to low energy spin dynamics defining the ground state properties and is useful in mapping the tomography of correlated electron materials. NMR is a powerful microscopic probe to extract the intrinsic magnetic susceptibility and to probe topological order and elucidate the nature of enigmatic elementary excitations in correlated quantum matter. NMR shares an interface with muon spin relaxation (µSR) and neutron scattering and the combination of these techniques on a complementary scale provides an outstanding track to shed insights into the dynamics of dressed quasi-particles in the ground state of correlated electron materials. In this short review, we focus on some of the emergent physical phenomena in a few correlated electron materials sharing common experimental signatures in magnetization, specific heat, and NMR spin susceptibility and spin lattice relaxation rates. © 2019 Elsevier B.V.

Journal of Magnetism and Magnetic Materials

Novel magnetism and spin dynamics of strongly correlated electron systems: Microscopic insights

Stripe order on the spin-1 stacked honeycomb lattice inBa2Ni(PO4)2

We investigate the magnetic, thermal, and dielectric properties of SrCuTe2O6, which is isostructural to PbCuTe2O6, a recently found, Cu-based 3D frustrated magnet with a corner-sharing triangular spin network having dominant first and second nearest neighbor (nn) couplings (Koteswararao et al 2014 Phys. Rev. B 90 035141). Although SrCuTe2O6 has a structurally similar spin network, the magnetic data exhibit the characteristic features of a typical quasi-1D magnet, which mainly resulted from the magnetically dominant third nn coupling, uniform chains. The magnetic properties of this system are studied via magnetization (M), heat capacity (C p), dielectric constant (ε'), and measurements along with ab initio band structure calculations. The magnetic susceptibility data show a broad maximum at 32 K and the system orders at low temperatures TN1 ≈ 5.5K and TN2 ≈ 4.5K, respectively. The analysis of the x(T) data gives an intra-chain coupling, J3/kB, to be about ≈ - 42 K with non-negligible frustrated inter-chain couplings (J1/kB and J2/kB ). The hopping parameters obtained from the LDA band structure calculations also suggest the presence of coupled uniform chains. The observation of simultaneous anomalies in ε'(T)at TN1 and T2 suggests the presence of a magneto-dielectric effect in SrCuTe2O6. A magnetic phase diagram is also built based on the M, C p, and results. © 2015 IOP Publishing Ltd.

Journal of Physics Condensed Matter

Observation of S = 1/2 quasi-1D magnetic and magneto-dielectric behavior in a cubic SrCuTe2O6

Reviews of Modern Physics

Erratum: Bose-Einstein condensation in quantum magnets [Rev. Mod. Phys.86, 563 (2014)]

Nature Physics

Quantum and classical criticality in a dimerized quantum antiferromagnet

Physical Review Letters

Successive Magnetic Phase Transitions and Multiferroicity in the Spin-One Triangular-Lattice AntiferromagnetBa3NiNb2O9

Bose-Einstein condensation of triplons in the S=1 tetramer antiferromagnet K2Ni2(MoO4)3: A compound close to a quantum critical point

Journal	Data powered by TypesetPhysical Review B
Publisher	Data powered by TypesetAmerican Physical Society
ISSN	24699950
Open Access	No