Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAnomalous Hall effect at the spontaneously electron-doped polar surface of PdCoO2 ultrathin films
147
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We revealed the electrical transport through surface ferromagnetic states of a nonmagnetic metal PdCoO2. Electronic reconstruction at the Pd-terminated surface of PdCoO2 induces Stoner-like ferromagnetic states, which could lead to spin-related phenomena among the highly conducting electrons in PdCoO2. Fabricating a series of nanometer-thick PdCoO2 thin films, we detected a surface-magnetization-driven anomalous Hall effect via systematic thickness- and termination-dependent measurements. Besides, we discuss that finite magnetic moments in electron doped CoO2 triangular lattices may have given rise to additional unconventional Hall resistance.
rate research
Read More
We report on the successful synthesis of highly conductive PdCoO2 ultrathin films on Al2O3 (0001) by pulsed laser deposition. The thin films grow along the c-axis of the layered delafossite structure of PdCoO2, corresponding to the alternating stacking of conductive Pd layers and CoO2 octahedra. The thickness-dependent transport measurement reveals that each Pd layer has a homogeneous sheet conductance as high as 5.5 mS in the samples thicker than the critical thickness of 2.1 nm. Even at the critical thickness, high conductivity exceeding 104 Scm-1 is achieved. Optical transmittance spectra exhibit high optical transparency of PdCoO2 thin films particularly in the near-infrared region. The concomitant high values of electrical conductivity and optical transmittance make PdCoO2 ultrathin films as promising transparent electrodes for triangular-lattice-based materials.
We predict spin Hall angles up to 80% for ultrathin noble metal films with substitutional Bi impurities. The colossal spin Hall effect is caused by enhancement of the spin Hall conductivity in reduced sample dimension and a strong reduction of the charge conductivity by resonant impurity scattering. These findings can be exploited to create materials with high efficiency of charge to spin current conversion by strain engineering.
We report on the experimental observation of an anomalous Hall effect (AHE) in highly oriented pyrolytic graphite samples. The overall data indicate that the AHE in graphite can be self-consistently understood within the frameworks of the magnetic-field-driven excitonic pairing models.
A controversy arose over the interpretation of the recently observed hump features in Hall resistivity $rho_{xy}$ from ultra-thin SrRuO$_3$ (SRO) film; it was initially interpreted to be due to topological Hall effect but was later proposed to be from existence of regions with different anomalous Hall effect (AHE). In order to settle down the issue, we performed Hall effect as well as magneto-optic Kerr-effect measurements on 4 unit cell SRO films grown on SrTiO$_3$ (001) substrates. Clear hump features are observed in the measured $rho_{xy}$, whereas neither hump feature nor double hysteresis loop is seen in the Kerr rotation which should be proportional to the magnetization. In addition, magnetization measurement by superconducting quantum interference device shows no sign of multiple coercive fields. These results show that inhomogeneous AHE alone cannot explain the observed hump behavior in $rho_{xy}$ data from our SRO ultra-thin films. We found that emergence of the hump structure in $rho_{xy}$ is closely related to the growth condition, high quality films having clear sign of humps.
We report on the electronic structure of $alpha$-Sn films in the very low thickness regime grown on InSb(111)A. High-resolution low photon energies angle-resolved photoemission (ARPES) allows for the direct observation of the linearly dispersing 2D topological surface states (TSSs) that exist between the second valence band and the conduction band. The Dirac point of this TSS was found to be 200meV below the Fermi level in 10-nm-thick $alpha$-Sn films, which enables the observation of the hybridization gap opening at the Dirac point of the TSS for thinner films. The crossover to a quasi-2D electronic structure is accompanied by a full gap opening at the Brillouin zone center, in agreement with our density functional theory calculations. We further identify the thickness regime of $alpha$-Sn films where the hybridization gap in TSS coexists with the topologically non-trivial electronic structure and one can expect the presence of a 1D helical edge states.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
