Electronic picture of spin-polarized tunneling with a Cr tip

Czerner, Michael; Rodary, Guillemin; Wedekind, Sebastian; Fedorov, D. V.; Sander, Dirk; Mertig, Ingrid; Kirschner, J.

doi:10.1016/j.jmmm.2009.09.041

Cited by 7 publications

(5 citation statements)

References 15 publications

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“…To reduce the magnetic stray field effect, bulk antiferromagnetic materials are good candidates for tips in SP-STM and, indeed, bulk Cr tips were successfully used as SP-STM tips (Li Bassi et al, 2007;Schlenhoff et al, 2010;Corbetta et al, 2012). Corbetta et al (2012) revealed that the spin orientation of the apex of bulk Cr tips can be controlled by external magnetic fields due to the presence of uncompensated magnetic moments at the tip apex (Payne, Jiang, and Bloomfield, 2006;Czerner et al, 2010). The tips most commonly used for SP-STM measurements are W tips covered with magnetic materials.…”

Section: A Magnetic Materialsmentioning

confidence: 99%

Spin-polarized quantum confinement in nanostructures: Scanning tunneling microscopy

et al. 2014

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Experimental investigations of spin-polarized electron confinement in nanostructures by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) are reviewed. To appreciate the experimental results on the electronic level, the physical basis of STM is elucidated with special emphasis on the correlation between differential conductance, as measured by STS, and the electron density of states, which is accessible in ab initio theory. Experimental procedures which allow one to extract the electron dispersion relation from energy-dependent and spatially resolved STM and STS studies of electron confinement are reviewed. The role of spin polarization in electron confinement is highlighted by both experimental and theoretical insights, which indicate variation of the spin polarization in sign and magnitude on the nanometer scale. This review provides compelling evidence for the necessity to include spatial-dependent spin-resolved electronic properties for an in-depth understanding and quantitative assessment of electron confinement in magnetic nanostructures and interaction between magnetic adatoms.

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Section: A Magnetic Materialsmentioning

confidence: 99%

Spin-polarized quantum confinement in nanostructures: Scanning tunneling microscopy

et al. 2014

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“…Indeed, uncompensated magnetic moments in Cr clusters have already been observed experimentally 20) and treated theoretically. 21) To determine the spin polarization of the tip (P t ), we measured the energy dependence of the dI=dV asymmetry A on a single Co island for parallel (P) and anti-parallel (AP) orientations between tip and sample magnetic moments. The result is shown in Fig.…”

mentioning

confidence: 99%

Magnetic Response and Spin Polarization of Bulk Cr Tips for In-Field Spin-Polarized Scanning Tunneling Microscopy

Corbetta

Ouazi

Borme

et al. 2012

Jpn. J. Appl. Phys.

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In non-abelian gauge theories without matter fields, expectation values of large Wilson loops and loop correlation functions are difficult to compute through numerical simulation, because the signal-to-noise ratio is very rapidly decaying for increasing loop sizes. Using a multilevel scheme that exploits the locality of the theory, we show that the statistical errors in such calculations can be exponentially reduced. We explicitly demonstrate this in the SU(3) theory, for the case of the Polyakov loop correlation function, where the efficiency of the simulation is improved by many orders of magnitude when the area bounded by the loops exceeds 1 fm 2 .

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“…Regular tunneling spectroscopic studies were conducted with atomically sharp Pt/Ir tips, while spin-polarized studies were made by means of Pt/Ir tips evaporatively coated with 15-30 monolayers of Cr metal prepared in a separate evaporation system, following the procedures reported previously. 29,30 Here we note that thin-film Cr is ferromagnetic 29,30 and the Curie temperature ͑T C Cr ͒ of our Cr-coated tip was found to be much higher than room temperature. Therefore, it is justifiable to assume that electrical currents from the Cr-coated tip were always spin polarized.…”

Section: Methodsmentioning

confidence: 67%

“…To address the aforementioned issues of phase separations, insulating surface layers and the PG phenomena in the manganites, we report in this work spatially resolved tunneling spectroscopic studies of La 0.7 Ca 0.3 MnO 3 (LCMO) epitaxial films by means of both regular and spin-polarized scanning tunneling microscopy [29][30][31][32][33] (STM and SP-STM). The specific calcium doping level of x = 0.3 was chosen because it corresponded to a nominal metallic phase with nearly the highest Curie temperature (T C ∼ 270 K) and the most spatial homogeneity among the Ca-doped manganites.…”

Section: Introductionmentioning

confidence: 99%

Spin-polarized tunneling spectroscopic studies of the intrinsic heterogeneity and pseudogap phenomena in colossal magnetoresistive manganiteLa0.7Ca0.3MnO3
Hughes
¹
,
Beyer
²
,
Yeh
³

2010
Phys. Rev. B
6
0
2
0
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Spatially resolved tunneling spectroscopic studies of colossal magnetoresistive ͑CMR͒ manganite La 0.7 Ca 0.3 MnO 3 ͑LCMO͒ epitaxial films on ͑LaAlO 3 ͒ 0.3 ͑Sr 2 AlTaO 6 ͒ 0.7 substrate are investigated as functions of temperature, magnetic field and spin polarization by means of scanning tunneling spectroscopy. Systematic surveys of the tunneling spectra taken with Pt/Ir tips reveal spatial variations on the length scale of a few hundred nanometers in the ferromagnetic state, which may be attributed to the intrinsic heterogeneity of the manganites due to their tendency toward phase separation. The electronic heterogeneity is found to decrease either with increasing field at low temperatures or at temperatures above all magnetic ordering temperatures. On the other hand, spectra taken with Cr-coated tips are consistent with convoluted electronic properties of both LCMO and Cr. In particular, for temperatures below the magnetic ordering temperatures of both Cr and LCMO, the magnetic field-dependent tunneling spectra may be quantitatively explained by the scenario of spin-polarized tunneling in a spin-valve configuration. Moreover, a low-energy insulating energy gap ϳ0.6 eV commonly found in the tunneling conductance spectra of bulk metallic LCMO at T → 0 may be attributed to a surface ferromagnetic insulating phase, as evidenced by its spin-filtering effect at low temperatures and vanishing gap value above the Curie temperature. Additionally, temperature-independent pseudogap ͑PG͒ phenomena existing primarily along the boundaries of magnetic domains are observed in the zero-field tunneling spectra. The PG becomes strongly suppressed by applied magnetic fields at low temperatures when the tunneling spectra of LCMO become highly homogeneous. These findings suggest that the occurrence PG is associated with the electronic heterogeneity of the manganites. The observation of lateral and vertical electronic heterogeneity in the CMR manganites places important size constraints on the development of highdensity nanoscale spintronic devices based on these materials.

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Electronic picture of spin-polarized tunneling with a Cr tip

Cited by 7 publications

References 15 publications

Spin-polarized quantum confinement in nanostructures: Scanning tunneling microscopy

Spin-polarized quantum confinement in nanostructures: Scanning tunneling microscopy

Magnetic Response and Spin Polarization of Bulk Cr Tips for In-Field Spin-Polarized Scanning Tunneling Microscopy

Spin-polarized tunneling spectroscopic studies of the intrinsic heterogeneity and pseudogap phenomena in colossal magnetoresistive manganiteLa0.7Ca0.3MnO3
Hughes
¹
,
Beyer
²
,
Yeh
³

2010
Phys. Rev. B
6
0
2
0
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Electronic picture of spin-polarized tunneling with a Cr tip

Cited by 7 publications

References 15 publications

Spin-polarized quantum confinement in nanostructures: Scanning tunneling microscopy

Spin-polarized quantum confinement in nanostructures: Scanning tunneling microscopy

Magnetic Response and Spin Polarization of Bulk Cr Tips for In-Field Spin-Polarized Scanning Tunneling Microscopy

Spin-polarized tunneling spectroscopic studies of the intrinsic heterogeneity and pseudogap phenomena in colossal magnetoresistive manganiteLa0.7Ca0.3MnO3Hughes1, Beyer2, Yeh3 2010Phys. Rev. B6020View full textAdd to dashboardCite

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Spin-polarized tunneling spectroscopic studies of the intrinsic heterogeneity and pseudogap phenomena in colossal magnetoresistive manganiteLa0.7Ca0.3MnO3
Hughes
¹
,
Beyer
²
,
Yeh
³

2010
Phys. Rev. B
6
0
2
0
View full text Add to dashboard Cite