A5051153536- Topological Materials and Phenomena
- Rare-earth and actinide compounds
- Iron-based superconductors research
- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- Graphene research and applications
- Quantum many-body systems
- Superconductivity in MgB2 and Alloys
- Theoretical and Computational Physics
- Diamond and Carbon-based Materials Research
- Boron and Carbon Nanomaterials Research
- Quasicrystal Structures and Properties
- Inorganic Chemistry and Materials
- Nanoparticle-Based Drug Delivery
- Superconducting Materials and Applications
- Magnetic Properties of Alloys
- Electronic and Structural Properties of Oxides
- Characterization and Applications of Magnetic Nanoparticles
- Orbital Angular Momentum in Optics
- Plasmonic and Surface Plasmon Research
- Iron oxide chemistry and applications
- Mechanical and Optical Resonators
Iowa State University
2018-2024
Ames National Laboratory
2018-2024
North South University
2018
University of Rajshahi
2001-2009
CaMn$_2$P$_2$ exemplifies the realization of a frustrated $J_1$-$J_2$-$J_3$ Heisenberg model corrugated honeycomb magnetic lattice. Previous studies show that below N\'eel temperature ($T_{\rm N}$), system forms cycloidal $6\times 6$ $ab$-plane unit cell conforms with various space groups. Here, we present single-crystal neutron-diffraction across expansive reciprocal-space volumes, confirming structure while uncovering further distinctive features. We find evidence for three domains,...
Magnetic defects play an important, but poorly understood, role in magnetic topological insulators (TIs). For example, surface transport and bulk properties are controlled by Bi2 Se3 -based dilute ferromagnetic (FM) TIs MnBi2 Te4 (MBT)-based antiferromagnetic (AFM) TIs. Despite its nascent ferromagnetism, the inelastic neutron scattering data show that a fraction of Mn Sb2 Te3 form strong AFM dimer singlets within quintuple block. The superexchange coupling occurs via Mn-Te-Mn linear bonds...
Eu-based Zintl-phase materials $\mathrm{Eu}{A}_{2}P{n}_{2}$ $(A=\mathrm{Mg},\mathrm{In},\mathrm{Cd},\mathrm{Zn};Pn=\mathrm{Bi},\mathrm{Sb},\mathrm{As},\mathrm{P})$ have generated significant recent interest owing to the complex interplay of magnetism and band topology. Here, we investigated crystallographic, magnetic, electronic properties layered single crystals ${\mathrm{EuMg}}_{2}{\mathrm{Sb}}_{2}$ with trigonal ${\mathrm{CaAl}}_{2}{\mathrm{Si}}_{2}$ crystal structure (space group...
The magnetic and electronic properties of the layered Zintl-phase compound EuAl$_2$Ge$_2$ crystallizing in trigonal CaAl$_2$Si$_2$-type structure are reported. Our neutron-diffraction measurements show that undergoes A-type antiferromagnetic (AFM) ordering below $T_{\rm N} = 27.5(5)$~K, with Eu moments (Eu$^{2+}$, $S 7/2$) aligned ferromagnetically $ab$ plane. $H 0$ consists AFM domains associated $ab$-plane anisotropy a field-induced reorientation spins is evident at $T 2$~K critical field...
We report on the crystal and magnetic structures transport properties of ${\mathrm{SrMnSb}}_{2}$ single crystals grown by self-flux method. Magnetic susceptibility measurements reveal an antiferromagnetic (AFM) transition at ${T}_{\mathrm{N}}=295(3)$ K. Above ${T}_{\mathrm{N}}$, slightly increases forms a broad peak $T\ensuremath{\sim}420$ K, which is typical feature two-dimensional systems. Neutron diffraction confirm previously reported C-type AFM structure below ${T}_{\mathrm{N}}$. Both...
Investigations of elastic properties Li3N in both α- and β-phases have been made by first-principles methods (HF-LCAO, DFT as implemented CRYSTAL98 CASTEP). The theoretical equation state the α-phase (D46h structure) produced our total-energy calculations is compared with experimental EOS. Five independent constants are calculated for first time phases. These available four α-Li3N estimated from slopes acoustic branches long wavelength region measured phonon dispersion curves. aggregate...
We report neutron-diffraction results on single-crystal ${\mathrm{CaMn}}_{2}{\mathrm{P}}_{2}$ containing corrugated Mn honeycomb layers, and we determine its ground-state magnetic structure. The diffraction patterns consist of prominent (1/6,1/6,$L$) reciprocal-lattice unit (r.l.u.; $L$ = integer) Bragg reflections, whose temperature-dependent intensities are consistent with a first-order antiferromagnetic phase transition at the N\'eel temperature ${T}_{\mathrm{N}}=70(1)$ K. Our analysis...
Near-field optical binding force is an emerging new topic in the field of manipulation and plasmonics. However, so far, all studies near-field its counterintuitive reversal are only restricted to dimer sets. In this work, we have studied extensively idea associated Lorentz dynamics for more than two objects, such as plasmonic tetramers over different substrates. We demonstrated that if closely positioned cube placed substrate circularly polarized light impinged them, all-optical control...
Inelastic neutron scattering (INS) from polycrystalline antiferromagnetic LaMnAsO, LaMnSbO, and BaMnAsF are analyzed using a $J_1-J_2-J_c$ Heisenberg model in the framework of linear spin-wave theory. All three systems show clear evidence that nearest- next-nearest-neighbor interactions within Mn square lattice layer ($J_1$ $J_2$) both (AFM). However, for all compounds studied competing have ratio $2J_2/J_1 < 1$, which favors checkerboard AFM structure over stripe structure. The inter-plane...
Abstract It is shown that magnetite nanoparticles (MagNPs) grafted with polyethylene glycol (PEG) self‐assemble and short‐range‐order as 2D films at surfaces of aqueous suspensions by manipulating salt concentrations. Synchrotron X‐ray reflectivity grazing‐incidence small angle scattering studies reveal K 2 CO 3 induces the migration PEG‐MagNPs to liquid/vapor interface form a Gibbs layer monoparticle in thickness. As concentration and/or nanoparticle increase, surface‐adsorbed become more...
Neutron diffraction and magnetic susceptibility studies show that orthorhombic single-crystals of topological semimetals $\mathrm{Sr}({\mathrm{Mn}}_{0.9}{\mathrm{Cu}}_{0.1}){\mathrm{Sb}}_{2}$ $\mathrm{Sr}({\mathrm{Mn}}_{0.9}{\mathrm{Zn}}_{0.1}){\mathrm{Sb}}_{2}$ undergo three-dimensional C-type antiferromagnetic (AFM) ordering the ${\mathrm{Mn}}^{2+}$ moments at ${T}_{N}=200\ifmmode\pm\else\textpm\fi{}10$ $210\ifmmode\pm\else\textpm\fi{}12$ K, respectively, significantly lower than parent...
Neutron diffraction and magnetic susceptibility studies of orthorhombic single crystal $({\mathrm{Sr}}_{0.97}{\mathrm{K}}_{0.03}){\mathrm{MnSb}}_{2}$ confirm the three-dimensional (3D) C-type antiferromagnetic (AFM) ordering ${\mathrm{Mn}}^{2+}$ moments at ${T}_{\mathrm{N}}=305\ifmmode\pm\else\textpm\fi{}3$ K, which is slightly higher than that parent ${\mathrm{SrMnSb}}_{2}$ with ${T}_{\mathrm{N}}=297\ifmmode\pm\else\textpm\fi{}3$ K. Susceptibility measurements K-doped crystals above...
We report on our attempt to hole-dope the antiferromagnetic semiconductor LaMnAsO by substitution of ${\mathrm{La}}^{3+}$ site ${\mathrm{Ca}}^{2+}$. use neutron and x-ray diffraction, magnetic susceptibility, transport techniques characterize polycrystalline $({\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x})\mathrm{MnAsO}$ samples prepared solid-state reaction find that parent compound is highly resistant with an upper limit $x\ensuremath{\le}0.01$. Magnetic susceptibility...
The addition of magnetic impurities in topological insulators can drive ferromagnetic order that leads to novel quantum anomalous Hall transport well below the Curie temperature. fragility quantized regime has been ascribed random nature moment distribution. Here, we refine this hypothesis by using inelastic neutron scattering and density-functional theory calculations show two antagonistic components define magnetism Mn-substituted SnTe, thereby limiting effectiveness dilute TIs. One...
Abstract Magnetic dopants in three-dimensional topological insulators (TIs) offer a promising avenue for realizing the quantum anomalous Hall effect (QAHE) without necessity an external magnetic field. Understanding relationship between site occupancy of dopant elements and their on macroscopic property is crucial controlling QAHE. By combining atomic-scale energy-dispersive X-ray spectroscopy (EDS) maps obtained by aberration-corrected scanning transmission electron microscopy (AC-STEM)...
The development of long-range ferromagnetic (FM) order in dilute magnetic topological insulators can induce dissipationless electronic surface transport via the quantum anomalous Hall effect. We measure excitations a prototypical crystalline insulator, ${\mathrm{Sn}}_{0.95}{\mathrm{Mn}}_{0.05}\mathrm{Te}$, using inelastic neutron scattering. Neutron diffraction and magnetization data indicate that our ${\mathrm{Sn}}_{0.95}{\mathrm{Mn}}_{0.05}\mathrm{Te}$ sample has no FM above temperature 2...
Abstract We report neutron-diffraction results on single-crystal CaMn 2 P containing corrugated Mn honeycomb layers and determine its ground-state magnetic structure. The diffraction patterns consist of prominent (1/6, 1/6, L) reciprocal lattice unit (r.l.u.; L = integer) Bragg reflections, whose temperature-dependent intensities are consistent with a first-order antiferromagnetic phase transition at the Néel temperature T N 70(1) K. Our analysis reveals an in-plane 6 × cell ordered spins...
The magnetic and electronic properties of the layered Zintl-phase compound EuAl$_2$Ge$_2$ crystallizing in trigonal CaAl$_2$Si$_2$-type structure are reported. Our neutron-diffraction measurements show that undergoes A-type antiferromagnetic (AFM) ordering below $T_{\rm N} = 27.5(5)$~K, with Eu moments (Eu$^{2+}$, $S 7/2$) aligned ferromagnetically $ab$ plane. $H 0$ consists AFM domains associated $ab$-plane anisotropy a field-induced reorientation spins is evident at $T 2$~K critical field...
Magnetic Topological Insulators Inelastic neutron scattering measurements, as reported by Farhan Islam and co-workers in article number 2209951, reveal the formation of linear Mn–Te–Mn antiferromagnetic dimers Mn-doped Sb2Te3 magnetic topological insulators, following Goodenough–Kanamori superexchange rule. The experiments also identify ferromagnetic correlations within quintuple blocks across van der Waals gap, which mediate long-range order. These competing interactions explain role...