A5002951974- Magnetism in coordination complexes
- Magnetic and transport properties of perovskites and related materials
- X-ray Diffraction in Crystallography
- Lanthanide and Transition Metal Complexes
- Crystallization and Solubility Studies
- Advanced Thermoelectric Materials and Devices
- Quantum and electron transport phenomena
- Advanced NMR Techniques and Applications
- Magnetic properties of thin films
- Electron Spin Resonance Studies
- Advanced Condensed Matter Physics
- Electronic and Structural Properties of Oxides
- Crystal Structures and Properties
- Organic and Molecular Conductors Research
- Topological Materials and Phenomena
- High-pressure geophysics and materials
- Glass properties and applications
- Solid-state spectroscopy and crystallography
- Rare-earth and actinide compounds
- Physics of Superconductivity and Magnetism
- Thermal properties of materials
- Advanced MRI Techniques and Applications
- 2D Materials and Applications
- Photorefractive and Nonlinear Optics
- Ferroelectric and Piezoelectric Materials
Oak Ridge National Laboratory
2020-2024
University of Tennessee at Knoxville
2018-2022
Knoxville College
2018
Spin-phonon coupling plays an important role in single-molecule magnets and molecular qubits. However, there have been few detailed studies of its nature. Here, we show for the first time distinct couplings g phonons CoII(acac)2(H2O)2 (acac = acetylacetonate) deuterated analogs with zero-field-split, excited magnetic/spin levels (Kramers doublet (KD)) S 3/2 electronic ground state. The are observed as avoided crossings magnetic-field-dependent Raman spectra constants 1-2 cm-1. Far-IR reveal...
High-entropy oxides (HEOs) have aroused growing interest due to fundamental questions relating their structure formation, phase stability, and the interplay between configurational disorder physical chemical properties. Introducing Fe(II) Mn(II) into a rocksalt HEO is considered challenging, as theoretical analysis suggests that they are unstable in this under ambient conditions. Here, we develop bottom-up method for synthesizing Mn- Fe-containing (FeO-HEO). We present comprehensive...
The field of spintronics has seen a surge interest in altermagnetism due to novel predictions and many possible applications. MnTe is leading altermagnetic candidate that significant across its layered antiferromagnetic structure, high Neel temperature (TN ~ 310 K) semiconducting properties. We present results on molecular beam epitaxy (MBE) grown MnTe/InP(111) films. Here, it found the electronic magnetic properties are driven by natural stoichiometry MnTe. Electronic transport situ...
Spin–phonon coupling plays a critical role in magnetic relaxation single-molecule magnets (SMMs) and molecular qubits. Yet, few studies of its nature have been conducted. Phonons here refer to both intermolecular intramolecular vibrations. In the current work, we show spin–phonon couplings between IR-active phonons lanthanide complex Kramers doublets (from crystal field). For SMM Er[N(SiMe3)2]3 (1, Me = methyl), are observed far-IR magnetospectroscopy (FIRMS) crystals with constants ≈ 2–3...
Abstract Large separation of magnetic levels and slow relaxation in metal complexes are desirable properties single‐molecule magnets (SMMs). Spin‐phonon coupling (interactions with phonons) is ubiquitous, leading to loss memory SMMs quantum coherence qubits. Direct observation transitions spin‐phonon molecules challenging. We have found that far‐IR spectra (FIRMS) Co(PPh 3 ) 2 X ( Co‐X ; X=Cl, Br, I) reveal rarely observed as avoided crossings between u ‐symmetry phonon transitions....
While progress in thermoelectric materials based on the engineering of electronic and phononic characteristics is reaching a plateau, addition spin degree freedom has potential to open new landscape for alternative materials. Here, we present concepts, current understanding, guidelines designing spin-driven thermoelectrics. We show that interplay between heat currents entropy transport via charge carriers can offer path enhance thermopower. The classical antiferromagnetic semiconductor...
The authors show that minuscule amounts of Li suffice to tune antiferromagnetic MnTe from an easy-plane easy-axis material. Upon heating towards the N\'eel temperature 307 K, spins do not gradually rotate back a planar orientation, and instead maintain their axial orientation up relatively high 260 before quickly switching crossing into paramagnetic phase. Calculations indicate bears two competing magnetic ground states which can be manipulated by slightly shifting Fermi level via Li-doping....
Large separations between ground and excited magnetic states in single-molecule magnets (SMMs) are desirable to reduce the likelihood of spin reversal molecules. Spin-phonon coupling is a process leading relaxation. Both coupling, making SMMs lose moments, undesirable. However, direct determination large (>45 cm-1 ) challenging, few detailed investigations spin-phonon have been conducted. The separation [Co(12-crown-4)2 ](I3 )2 (12-crown-4) (1) determined its probed by inelastic neutron...
A combination of inelastic neutron scattering (INS), far-IR magneto-spectroscopy (FIRMS), and Raman (RaMS) has been used to comprehensively probe magnetic excitations in Co(AsPh3)2I2 (1), a reported single-molecule magnet (SMM). With applied field, the zero-field splitting (ZFS) peak (2D') shifts higher energies each spectroscopy. INS placed ZFS at 54 cm-1, as revealed by both variable-temperature (VT) variable-magnetic-field data, giving results that agree well with those from studies. Both...
Manganese telluride (MnTe) is a prospective platform for ultrafast carrier dynamics, spin-based thermoelectrics, and magnon-drag transport due to its unique electronic magnetic properties. We use inelastic neutron scattering study both pure lithium-doped MnTe, focusing on the influence of doping in opening magnon gap. powder diffraction determine critical exponents phase transition Li-doped MnTe complement this information with muon spin rotation/relaxation. The gap reorientation mainly...
As a two-dimensional structural motif, the kagome net produces many interesting magnetic and electronic properties. In particular, this lattice flat bands with large density of states. When chemical potential is positioned within these bands, instabilities can result. For metal CoSn, alignment not realized, are completely filled, compound Pauli paramagnet. We have grown crystals powders CoSn1 – xInx shown that replacing Sn moves into band region, as expected from simple electron counting....
Quasiparticle physics underlies our understanding of the microscopic dynamical behaviors materials that govern a vast array properties, including structural stability, excited states and interactions, structure factors, electron phonon conductivities. Thus, band structures quasiparticle interactions is foundational to study condensed matter. Here we advance 'twist' description quasiparticles (including phonons Bloch electrons) in non-symmorphic chiral achiral materials. Such often have...
Co(acac) 2 (H O) ( 1 , acac = acetylacetonate), a transition metal complex S 3/2), displays field‐induced slow magnetic relaxation as single‐molecule magnet. For and its isotopologues (D 1‐ d 4 ) Co(acac‐ 7 18 in approximately D h symmetry, zero‐field splitting of the ground electronic state leads to two Kramers doublets (KDs): lower energy M ±1/2 ϕ 1,2 higher ±3/2 3,4 states. This work employs inelastic neutron scattering (INS), unique method probe transitions, different excitations ....
Methyl rotation in a paramagnetic Co(II) complex is slowed down by magnetic field with an increased barrier.
The characterization of simple elemental systems is key to benchmarking first-principles modeling electronic and vibrational behaviors materials. A large body literature has been built for most in the periodic table. However, surprisingly little neutron work performed probe properties iridium, likely due its absorption cross section. Nonetheless, iridium significant scientific technological interest relativistic electron effects electron-phonon coupling, particularly strongly correlated...
Phonons and their interactions are critically important for a variety of energy-relevant applications ranging from low thermal resistance substrates to barrier coatings. Fundamental insights into the nature phonons allowed governed by underlying symmetries crystal lattice. In this paper, we provide comprehensive detailed description lattice dynamics derived twist chiral achiral crystals---twist dynamics. Phonon bands naturally carry quantized angular momentum rotational phases, which give...
Two-dimensional (2D) coordination polymer (CP) [CoIII(CN)6]2[CoII(TODA)]3·7H2O (TODA = 1,4,10-trioxa-7,13-diazacyclopentadecane, Co-TODA) was reported earlier to show field-induced slow magnetic relaxation, displaying single-ion magnet (SIM) behaviors. Most SIMs are molecular compounds with fewer adopting or metal–organic framework (MOF) structures. In the current work, and phonon properties of Co-TODA have been studied by advanced spectroscopies computations. The combined use far-IR...
α-Sb2O3 (senarmontite), β-Sb2O3 (valentinite), and α-TeO2 (paratellurite) are compounds with pronounced stereochemically active Sb Te lone pairs. The vibrational lattice properties of each have been previously studied but often lead to incomplete or unreliable results due modes being inactive in infrared Raman spectroscopy. Here, we present a study the relationship between bonding dynamics these compounds. Mössbauer spectroscopy is used structure β-Sb2O3, whereas for oxide investigated using...
α-Sb2O4 (cervantite) and β-Sb2O4 (clinocervantite) are mixed valence compounds with equal proportions of SbIII SbV as represented in the formula SbIIISbVO4. Their structure properties can be difficult to calculate owing lone-pair electrons. Here, we present a study lattice dynamics vibrational using combination inelastic neutron scattering, Mössbauer spectroscopy, nuclear density functional theory (DFT) calculations. DFT calculations that account for electrons match experimental densities...
Invited for the cover of this issue are groups Zi-Ling Xue from University Tennessee, Yongqiang Cheng, Luke Daemen, Timmy Ramirez-Cuesta Oak Ridge National Laboratory, Craig Brown NIST Center Neutron Research and Delaware, Eckhard Bill Max Planck Institute Chemical Energy Conversion, Mihail Atanasov Frank Neese Coal General Inorganic Chemistry, Bulgarian Academy Sciences (MA). The image shows use inelastic neutron scattering (INS) to probe Zeeman splitting a single-molecule magnet (SMM)...
Abstract The field of spintronics has seen a surge interest in altermagnetism due to novel predictions and many possible applications. MnTe is leading altermagnetic candidate that significant across its layered antiferromagnetic structure, high Neel temperature ( T N ≈ 310 K) semiconducting properties. results on molecular beam epitaxy (MBE) grown MnTe/InP(111) films are presented. Here, it found the electronic magnetic properties driven by natural stoichiometry MnTe. Electronic transport...
Antimony oxides are important materials for catalysis and flame-retardant applications. The two most common phases, α-Sb2O3 (senarmontite) β-Sb2O3 (valentinite), have been studied extensively. Specific focus has placed recently on their lattice dynamics properties how they relate to the α-β phase transformation potential anharmonicity. However, there not any direct investigation of anharmonicity in these systems, a surprising lack low-temperature structural information prevented further...
Magnetic structure and crystal symmetry, which primarily determine the time-reversal inversion may give rise to numerous exotic quantum phenomena in magnetic semiconductors semimetals when arranged different patterns. In this work, a new layered semiconductor, Eu3−δZnxSnyAs3, was discovered high-quality single crystals were grown using Sn flux. According structural characterization by x-ray diffraction atomic-resolution scanning transmission electron microscopy, Eu3−δZnxSnyAs3 is found...