14 research outputs found
Resolving the spin polarization and magnetic domain wall width of (Nd,Dy)FeB with spin-polarized scanning tunneling microscopy
The electronic structure and the domain wall width of industrial (Nd,Dy)FeB hard magnets were investigated using low-temperature, spin-polarized scanning tunneling microscopy (STM) in ultra-high vacuum. In a first step, atomically clean and flat surfaces were prepared. The flat terraces were separated by monatomic steps. Surface termination was identified as the Fe c layer from atomically resolved STM imaging. The electronic density of states and its spin polarization agree well with ab initio predictions of the Fe c layer. High-resolution spin-polarized STM images allowed to finally resolve the domain wall width w of only 3.2 ± 0.4 nm
Seismic exploration at Fuji volcano with active sources : The outline of the experiment and the arrival time data
Fuji volcano (altitude 3,776m) is the largest basaltic stratovolcano in Japan. In late August and early September 2003, seismic exploration was conducted around Fuji volcano by the detonation of 500 kg charges of dynamite to investigate the seismic structure of that area. Seismographs with an eigenfrequency of 2 Hz were used for observation, positioned along a WSW-ENE line passing through the summit of the mountain. A total of 469 seismic stations were installed at intervals of 250-500 m. The data were stored in memory on-site using data loggers. The sampling interval was 4 ms. Charges were detonated at 5 points, one at each end of the observation line and 3 along its length. The first arrival times and the later-phase arrival times at each station for each detonation were recorded as data. P-wave velocities in the surface layer were estimated from the travel time curves near the explosion points, with results of 2.5 km/s obtained for the vicinity of Fuji volcano and 4.0 km5/s elsewhere
Fabrication of L10-type FeCo ordered structure using a periodic Ni buffer layer
We experimentally prepared a ferromagnet with an L10-FeCo ordered structure by inserting a periodic buffer layer to suppress the B2 structural transition and to maintain the L10 structure. The sample was fabricated by utilizing a technique involving the deposition of alternating monoatomic layers using pulsed laser deposition (PLD). This technique was used to deposit a thin film of (7 ML-FeCo/3 ML-buffer)3, in which either Cu or Ni was utilized as buffer layer. We characterized the surface roughness, surface morphology, lattice structure, and magnetic properties of the specimens by RHEED, AFM, SR-XRD, and SQUID, respectively. As a result, we successfully confirmed the construction of the L10-FeCo superstructure with a periodic Ni buffer layer for the first time. Both the magnetic moment and magnetic anisotropy were also increased by replacing Cu with Ni
Magnetic anisotropy and magnetic excitations in supported atoms
We present a view on inelastic scanning tunneling spectroscopy of magnetic impurities relying on states of the total angular momentum J = L + S in the presence of a crystal field. We show that the selection rules for spin-flip scattering within the J -multiplet agree with the simple selection rules for the effective spin model, but also show the deviations from the latter for the transition probabilities. A reinterpretation of some recent experimental findings in a description based on the total angular momentum J is done
Exchange Coupling of Spin-Crossover Molecules to Ferromagnetic Co Islands
The
properties of Fe(1,10-phenanthroline)<sub>2</sub>(NCS)<sub>2</sub> (Fe-phen) molecules deposited on Co/Cu(111) are studied with
scanning tunneling microscopy (STM) operated in ultrahigh vacuum at
low temperature (4 K) and ab initio calculations. Both the experimental
and theoretical results are used to identify the high-spin (HS) state
of Fe-phen. Additionally, the calculations reveal a strong spin-polarization
of the density of states (DOS) and is validated experimentally using
the spin sensitivity of spin-polarized STM. Finally, it is shown that
the magnetic moment of the Fe-ion within HS Fe-phen is strongly magnetically
coupled to the underlying magnetic Co through the NCS groups. These
findings enable promising spintronic perspectives
Modulation of Electron–Phonon Coupling in One-Dimensionally Nanorippled Graphene on a Macrofacet of 6H-SiC
Local
electron–phonon coupling of a one-dimensionally nanorippled
graphene is studied on a SiC(0001) vicinal substrate. We have characterized
local atomic and electronic structures of a periodically nanorippled
graphene (3.4 nm period) prepared on a macrofacet of the 6H-SiC crystal
using scanning tunneling microscopy/spectroscopy (STM/STS) and angle-resolved
photoelectron spectroscopy (ARPES). The rippled graphene on the macrofacets
distributes homogeneously over the 6H-SiC substrate in a millimeter
scale, and thus replica bands are detected by the macroscopic ARPES.
The STM/STS results indicate the strength of electron–phonon
coupling to the out-of-plane phonon at the <i>K̅</i> points of graphene is periodically modified in accordance with the
ripple structure. We propose an interface carbon nanostructure with
graphene nanoribbons between the surface rippled graphene and the
substrate SiC that periodically modifies the electron–phonon
coupling in the surface graphene