Multiferroics, defined for those multifunctional materials in which two or more kinds of fundamental ferroicities coexist, have become one the hottest topics condensed matter physics and science recent years. The coexistence several order parameters multiferroics brings out novel physical phenomena offers possibilities new device functions. revival research activities on is evidenced by some discoveries concepts, both experimentally theoretically. In this review, we outline progressive...

Perovskite-type polycrystalline BiFeO3 (BFO) nanowires (∼50nm in diameter and ∼5μm length) were synthesized using the anodized alumina template technique. An energy band gap of ∼2.5eV was determined from UV-visible diffuse reflectance spectrum, its photocatalytic ability to produce O2 revealed under UV irradiation. Weak ferromagnetism at room temperature superparamagnetism low observed for BFO nanowires, different antiferromagnetic order bulk BFO, reflecting significant size effects on...

The extremely large transverse magnetoreistance (the magnetoresistant ratio $\sim 1.3\times10^5\%$ in 2 K and 9 T field, $4.3\times 10^6\%$ 0.4 32 without saturation), the metal-semiconductor crossover induced by magnetic are reported NbSb$_2$ single crystal with electric current parallel to $b$-axis. is preserved when along $ac$-plane but significantly suppressed. sign reversal of Hall resistivity field close point, electronic structure calculation reveals coexistence a small number holes...

We report two-dimensional quantum transport in SrMnBi$_2$ single crystals. The linear energy dispersion leads to the unusual nonsaturated magnetoresistance since all Dirac fermions occupy lowest Landau level limit. transverse exhibits a crossover at critical field $B^*$ from semiclassical weak-field $B^2$ dependence high-field linear-field dependence. With increase temperature, increases and temperature of satisfies quadratic behavior which is attributed splitting dispersion. effective...

We report two-dimensional Dirac fermions and quantum magnetoresistance in single crystals of CaMnBi${}_{2}$. The nonzero Berry's phase, small cyclotron resonant mass, first-principles band structure suggest the existence Bi square nets. in-plane transverse exhibits a crossover at critical field ${B}^{*}$ from semiclassical weak-field ${B}^{2}$ dependence to high-field unsaturated linear ($\ensuremath{\sim}$$120%$ 9 T 2 K) due limit fermions. temperature satisfies quadratic behavior, which is...

Abstract The thermoelectric performance of materials relies substantially on the band structures that determine electronic and phononic transports, while transport behaviors compete counter-act for power factor PF figure-of-merit ZT . These issues make a full-scale computation whole set parameters particularly attractive, calculation scheme contributions to thermal conductivity remains yet challenging. In this work, we present based first-principles calculations by choosing doped...

Evidence of unconventional superconducting state in a topological semimetal confirms unprecedented spin-3/2 Cooper pairing.

Bi 5 Ti 3 Fe O 15 bulk ceramic and thin film samples are prepared using the sol-gel method. The dielectric, ferroelectric, magnetic behaviors of these measured in order to investigate possible multiferroic effect. superparamagnetic behavior with dominant antiferromagnetic (AFM) interaction background for as-prepared Bi5Ti3FeO15 is revealed. clearly identified magnetocapacitance effect at low temperature argued originate from suppression AFM by external field.

La 0.4 Ca 0.6 Mn O 3 nanoparticles of grain size as small ∼20nm are prepared and their magnetic behaviors investigated in order to understand the effect charge ordering manganites. The highly stable charge-ordered state can be significantly suppressed upon reduction down nanometer scale, while ferromagnetism is enhanced. phase separation due competition between ferromagnetic well surface spin disordering responsible for spin-glass-like at low temperature.

We have synthesized a new layered BiS2-based compound, SrFBiS2. This compound has similar structure to LaOBiS2. It is built up by stacking SrF layers and NaCl-type BiS2 alternatively along the c axis. Electric transport measurement indicates that SrFBiS2 semiconductor. Thermal shows small thermal conductivity large Seebeck coefficient. First principle calculations are in agreement with experimental results show very LaOBiS2, which becomes superconductor F doping. Therefore, may be parent of...

We report two-dimensional quantum transport and Dirac fermions in BaMnBi2 single crystals. is a layered bad metal with highly anisotropic conductivity magnetic order below 290 K. Magnetotransport properties, nonzero Berry phase, small cyclotronmass, the first-principles band structure calculations indicate presence of Bi square nets. Quantum oscillations Hall channel suggest both electron hole pockets, whereas parabolic states coexist at Fermi level.

We report structurally tuned superconductivity in KxFe2-ySe2-zSz (0<=z<=2) phase diagram. Superconducting Tc is suppressed as S incorporated into the lattice, eventually vanishing at 80% of S. The magnetic and conductivity properties can be related to stoichiometry on poorly occupied Fe1 site local environment nearly fully Fe2 site. decreasing coincides with increasing occupancy overall increase Fe from z = 0 2. Our results indicate that irregularity Fe2-Se/S tetrahedron an important...

Here we report the possible signature of Dirac fermions in magnetoresistance, Hall resistivity and magnetothermopower LaAgSb$_2$. The opposite sign between Seebeck coefficient indicates multiband effect. Electronic structure calculation reveals existence linear bands parabolic crossing Fermi level. large magnetoresistance was attributed to quantum limit or breakdown weak-field magnetotransport at charge density wave phase transition. Analysis using two-band model that holes which dominate...

Abstract Charge density wave (CDW), the periodic modulation of electronic charge density, will open a gap on Fermi surface that commonly leads to decreased or vanishing conductivity. On other hand superconductivity, believed competing order, features results in infinite Here we report superconductivity emerges upon Se doping CDW conductor ZrTe 3 when long range order is gradually suppressed. Superconducting critical temperature T c ( x ) 3− (0 ≤ 0.1) increases up 4 K plateau for 0.04 0.07....

The recently discovered large nonsaturating magnetoresistance in semimetal $\mathrm{WT}{\mathrm{e}}_{2}$ may result from near-perfect electron-hole compensation, however recent reports question whether the compensation is adequate to explain observations. Experiments on significantly uncompensated are needed. We measure ${\ensuremath{\rho}}_{xx}(H)$, Hall effect ${\ensuremath{\rho}}_{xy}(H)$, and an electrolyte gating thin (100 nm) exfoliated $\mathrm{WT}{\mathrm{e}}_{2}$. observe...

We report the optical conductivity in high-quality crystals of chiral topological semimetal CoSi, which hosts exotic quasiparticles known as multifold fermions. find that response is separated into several distinct regions a function frequency, each dominated by different types quasiparticles. The low-frequency intraband captured narrow Drude peak from high-mobility electron pocket double Weyl quasi-particles, and temperature dependence spectral weight consistent with its Fermi velocity. By...

The dependence of magnetotransport behaviors on $A$-site disorder induced by cational size mismatch in ferromagnetic manganites is investigated characterizing a series samples with the same mean radius $⟨{r}_{A}⟩=1.20\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ but different ionic radii variance ${\ensuremath{\sigma}}^{2}={\ensuremath{\sum}}_{i}{x}_{i}{r}_{i}^{2}\ensuremath{-}{⟨{r}_{A}⟩}^{2}$, where ${x}_{i}$ and ${r}_{i}$ are atomic fraction $i$-type ions at $A$-site, respectively. It...

We investigate in detail the migration kinetics of oxygen vacancies (OVs) Ba-doped Pb(Zr0.52Ti0.48)O3 (PZT) ferroelectrics by complex impedance spectroscopy. The temperature dependent dc-electrical conductivity σdc suggests that Ba doping into PZT can lower significantly density OVs, leading to distinctly decreased and slightly enhanced activation energy U for thus benefiting polarization fatigue resistance. Furthermore, fluctuation induced relaxation OVs is reduced doping. Cole–Cole fitting...

We report detailed Seebeck coefficient, Hall resistivity as well specific heat measurement on Ca$_3$Ir$_4$Sn$_{13}$ single crystals. The coefficient exhibits a peak corresponding to the anomaly in at $T^*$, and carrier density is suppressed significantly below $T^*$. This indicates significant Fermi surface reconstruction opening of charge wave gap supperlattice transition. magnetic field induced enhancement residual $\gamma(H)$ nearly linear dependence field, indicating nodeless gap. In...

We report quasi-two-dimensional Dirac fermions and quantum magnetoresistance in LaAgBi$_2$. The band structure shows several narrow bands with nearly linear energy dispersion Dirac-cone-like points at the Fermi level. oscillation experiments revealed one pocket another complex small cyclotron resonant mass. in-plane transverse exhibits a crossover critical field $B^*$ from semiclassical weak-field $B^2$ dependence to high-field unsaturated which is attributed limit of fermions. Our results...

Abstract One of the core issues for multiferroicity is strongly coupled ferroelectric polarization and magnetization, while so far most multiferroics have antiferromagnetic order with nearly zero magnetization. Magnetic spinel compounds ferrimagnetic may be alternative candidates offering large magnetization when ferroelectricity can activated simultaneously. In this work, we investigate magnetism FeCr 2 S 4 in which Fe 2+ sublattice Cr 3+ are antiparallel alignment. Well defined transitions...

The Wang-Landau algorithm is used to study the thermodynamic and magnetic properties of triangular spin-chain system based on two-dimensional Ising model in order understand magnetic-order dynamics ${\text{Ca}}_{3}{\text{Co}}_{2}{\text{O}}_{6}$ compound. calculated results demonstrate that equilibrium state rigid spins produces two-step magnetization curve at low temperature even when random-exchange term considered. This work indicates four-step behavior observed experimentally must be due...

Recently synthesized metastable tetragonal CoSe, isostructural to the FeSe superconductor, offers a new avenue for investigating systems in close proximity iron-based superconductors. We present magnetic and transport property measurements on powders single crystals of CoSe. High field susceptibility indicate suppression previously reported 10 K ferromagnetic transition with susceptibility, exhibiting time dependence below proposed transition. Dynamic scaling analysis yields critical...