Study of Integer Spin S = 1 in the Polar Magnet β-Ni(IO3)2

Polar magnetic materials exhibiting appreciable asymmetric exchange interactions can potentially host new topological states of matter such as vortex-like spin textures; however, realizations have been mostly limited to half-integer spins due to rare numbers of integer spin systems with broken spatial inversion lattice symmetries. Here, we studied the structure and magnetic properties of the S = 1 integer spin polar magnet β-Ni(IO3)2 (Ni2+, d8, 3F). We synthesized single crystals and bulk polycrystalline samples of β-Ni(IO3)2 by combining low-temperature chemistry techniques and thermal analysis and characterized its crystal structure and physical properties. Single crystal X-ray and powder X-ray diffraction measurements demonstrated that β-Ni(IO3)2 crystallizes in the noncentrosymmetric polar monoclinic structure with space group P21. The combination of the macroscopic electric polarization driven by the coalignment of the (IO3)− trigonal pyramids along the b axis and the S = 1 state of the Ni2+ cation was chosen to investigate integer spin and lattice dynamics in magnetism. The effective magnetic moment of Ni2+ was extracted from magnetization measurements to be 3.2(1) µB, confirming the S = 1 integer spin state of Ni2+ with some orbital contribution. β-Ni(IO3)2 undergoes a magnetic ordering at T = 3 K at a low magnetic field, μ0H = 0.1 T; the phase transition, nevertheless, is suppressed at a higher field, μ0H = 3 T. An anomaly resembling a phase transition is observed at T ≈ 2.7 K in the Cp/T vs. T plot, which is the approximate temperature of the magnetic phase transition of the material, indicating that the transition is magnetically driven. This work offers a useful route for exploring integer spin noncentrosymmetric materials, broadening the phase space of polar magnet candidates, which can harbor new topological spin physics.

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Tris(ethylenediamine) Cobalt(II) and Manganese(II) Nitrates

Crystals ◽

10.3390/cryst10060472 ◽

2020 ◽

Vol 10 (6) ◽

pp. 472

Author(s):

Miguel Cortijo ◽

Ángela Valentín-Pérez ◽

Mathieu Rouzières ◽

Rodolphe Clérac ◽

Patrick Rosa ◽

...

Keyword(s):

Phase Transition ◽

X Ray Diffraction ◽

Temperature Dependent ◽

Scanning Calorimetry ◽

Orbital Contribution ◽

X Ray ◽

Reversible Phase Transition ◽

Heat Capacity Measurements ◽

Reversible Phase

Octahedral tris(ethylenediamine) coordination complexes demonstrate helicoidal chirality, due to the arrangement of the ligands around the metal core. The enantiomers of the nitrate salts [Ni(en)3](NO3)2 and [Zn(en)3](NO3)2 spontaneously resolve to form a mixture of conglomerate crystals, which present a reversible phase transition from space group P6322 to enantiomorphic P6522 or P6122, with the latter depending on the handedness of the enantiomer. We report here the synthesis and characterization of [Mn(en)3](NO3)2 and [Co(en)3](NO3)2, which are isostructural to the Zn(II) and Ni(II) derivatives. The Mn(II) analogue undergoes the same phase transition centered at 150(2) K, as determined by single-crystal X-ray diffraction, Raman spectroscopy, and differential scanning calorimetry. The Co(II) derivative does not demonstrate a phase transition down to 2 K, as evidenced by powder X-ray diffraction and heat capacity measurements. The phase transition does not impact the magnetic properties of the Ni(II) and Mn(II) analogues; these high spin compounds display Curie behavior that is consistent with S = 1 and 5/2, respectively, down to 20 K, while the temperature-dependent magnetic moment for the Co(II) compound reveals a significant orbital contribution.

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Electron Microscope study of commensurate-incommensurate phase transition in BaZnGeO4

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100173996 ◽

1990 ◽

Vol 48 (4) ◽

pp. 172-173

Author(s):

Naoki Yamamoto ◽

Makoto Kikuchi ◽

Tooru Atake ◽

Akihiro Hamano ◽

Yasutoshi Saito

Keyword(s):

Phase Transition ◽

Electron Microscope Study ◽

Room Temperature ◽

Hexagonal Lattice ◽

Ferroelectric Materials ◽

Temperature Phase ◽

X Ray Diffraction ◽

X Ray ◽

Periodic Arrays ◽

Modulation Wave Vector

BaZnGeO4 undergoes many phase transitions from I to V phase. The highest temperature phase I has a BaAl2O4 type structure with a hexagonal lattice. Recent X-ray diffraction study showed that the incommensurate (IC) lattice modulation appears along the c axis in the III and IV phases with a period of about 4c, and a commensurate (C) phase with a modulated period of 4c exists between the III and IV phases in the narrow temperature region (—58°C to —47°C on cooling), called the III' phase. The modulations in the IC phases are considered displacive type, but the detailed structures have not been studied. It is also not clear whether the modulation changes into periodic arrays of discommensurations (DC’s) near the III-III' and IV-V phase transition temperature as found in the ferroelectric materials such as Rb2ZnCl4.At room temperature (III phase) satellite reflections were seen around the fundamental reflections in a diffraction pattern (Fig.1) and they aligned along a certain direction deviated from the c* direction, which indicates that the modulation wave vector q tilts from the c* axis. The tilt angle is about 2 degree at room temperature and depends on temperature.

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An FTIR and X‐ray diffraction study of the crystal phase transition in isotactic polybutene‐1

Polymer Crystallization ◽

10.1002/pcr2.10200 ◽

2021 ◽

Author(s):

Huiying Wen ◽

Hongshu Li ◽

Pengfei Qiao ◽

Chunxia Chen ◽

Shichun Jiang

Keyword(s):

Phase Transition ◽

Diffraction Study ◽

Crystal Phase ◽

X Ray Diffraction ◽

X Ray ◽

Crystal Phase Transition

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Pressure-induced Jahn-Teller Switch in the Homoleptic Hybrid Perovskite [(CH3)2NH2]Cu(HCOO)3: Orbital Reordering by Unconventional Degrees of Freedom

Journal of Materials Chemistry C ◽

10.1039/d1tc01966j ◽

2021 ◽

Author(s):

Rebecca Scatena ◽

Michał Andrzejewski ◽

Roger D Johnson ◽

Piero Macchi

Keyword(s):

Phase Transition ◽

High Pressure ◽

Coordination Polymer ◽

Degrees Of Freedom ◽

X Ray Diffraction ◽

X Ray ◽

Hybrid Perovskite ◽

Jahn Teller

Through in-situ, high-pressure x-ray diffraction experiments we have shown that the homoleptic perovskite-like coordination polymer [(CH3)2NH2]Cu(HCOO)3 undergoes a pressure-induced orbital reordering phase transition above 5.20 GPa. This transition is distinct...

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X-Ray Diffraction Analysis of the Amorphous–Crystalline Phase Transition in Ni

Technical Physics ◽

10.1134/s1063784220100102 ◽

2020 ◽

Vol 65 (10) ◽

pp. 1652-1658

Author(s):

D. Yu. Kovalev ◽

I. I. Chuev

Keyword(s):

Phase Transition ◽

Diffraction Analysis ◽

Crystalline Phase ◽

X Ray Diffraction ◽

X Ray ◽

Crystalline Phase Transition

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Emergent long-range magnetic order in ultrathin (111)-oriented LaNiO3 films

npj Quantum Materials ◽

10.1038/s41535-021-00345-2 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Margaret M. Kane ◽

Arturas Vailionis ◽

Lauren J. Riddiford ◽

Apurva Mehta ◽

Alpha T. N’Diaye ◽

...

Keyword(s):

Long Range ◽

Degrees Of Freedom ◽

Magnetic Order ◽

Magnetic Ordering ◽

Anomalous Hall Effect ◽

X Ray Diffraction ◽

X Ray ◽

Range Magnetic Order ◽

Film Substrate ◽

Long Range Magnetic Order

AbstractThe emergence of ferromagnetism in materials where the bulk phase does not show any magnetic order demonstrates that atomically precise films can stabilize distinct ground states and expands the phase space for the discovery of materials. Here, the emergence of long-range magnetic order is reported in ultrathin (111) LaNiO3 (LNO) films, where bulk LNO is paramagnetic, and the origins of this phase are explained. Transport and structural studies of LNO(111) films indicate that NiO6 octahedral distortions stabilize a magnetic insulating phase at the film/substrate interface and result in a thickness-dependent metal–insulator transition at t = 8 unit cells. Away from this interface, distortions relax and bulk-like conduction is regained. Synchrotron x-ray diffraction and dynamical x-ray diffraction simulations confirm a corresponding out-of-plane unit-cell expansion at the interface of all films. X-ray absorption spectroscopy reveals that distortion stabilizes an increased concentration of Ni2+ ions. Evidence of long-range magnetic order is found in anomalous Hall effect and magnetoresistance measurements, likely due to ferromagnetic superexchange interactions among Ni2+–Ni3+ ions. Together, these results indicate that long-range magnetic ordering and metallicity in LNO(111) films emerges from a balance among the spin, charge, lattice, and orbital degrees of freedom.

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Temperature-dependent synchrotron X-ray diffraction, pair distribution function and susceptibility study on the layered compound CrTe3

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2017-2100 ◽

2018 ◽

Vol 233 (6) ◽

pp. 361-370 ◽

Cited By ~ 1

Author(s):

Anna-Lena Hansen ◽

Bastian Dietl ◽

Martin Etter ◽

Reinhard K. Kremer ◽

David C. Johnson ◽

...

Keyword(s):

Distribution Function ◽

Pair Distribution Function ◽

Exchange Interactions ◽

Structural Distortion ◽

Layered Compound ◽

Minor Amount ◽

Zero Field ◽

X Ray Diffraction ◽

X Ray ◽

Anisotropic Expansion

Abstract Results of combined synchrotron X-ray diffraction and pair distribution function experiments performed on the layered compound CrTe3 provide evidence for a short range structural distortion of one of the two crystallographically independent CrTe6 octahedra. The distortion is caused by higher mobility of one crystallographically distinct Te ion, leading to an unusual large Debye Waller factor. In situ high temperature X-ray diffraction investigations show an initial crystallization of a minor amount of elemental Te followed by decomposition of CrTe3 into Cr5Te8 and Te. Additional experiments provide evidence that the Te impurity (<1%) cannot be avoided. Analyses of structural changes in the temperature range 100–754 K show a pronounced anisotropic expansion of the lattice parameters. The differing behavior of the crystal axes is explained on the basis of structural distortions of the Cr4Te16 structural building units. An abrupt distortion of the structure occurs at T≈250 K, which then remains nearly constant down to 100 K. The structural distortion affects the spin exchange interactions between Cr3+ cations. A significant splitting between field-cooled (fc) and zero-field-cooled (zfc) magnetic susceptibility is observed below about 200 K. Applying a small external magnetic field results in a substantial spontaneous magnetization, reminiscent of ferro- or ferrimagnet exchange interactions below ~240 K. A Debye temperature of ~150 K was extracted from heat capacity measurements.

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