38 research outputs found
Giant magnetoresistance in semiconductor / granular film heterostructures with cobalt nanoparticles
We have studied the electron transport in SiO(Co)/GaAs and
SiO(Co)/Si heterostructures, where the SiO(Co) structure is the
granular SiO film with Co nanoparticles. In SiO(Co)/GaAs
heterostructures giant magnetoresistance effect is observed. The effect has
positive values, is expressed, when electrons are injected from the granular
film into the GaAs semiconductor, and has the temperature-peak type character.
The temperature location of the effect depends on the Co concentration and can
be shifted by the applied electrical field. For the SiO(Co)/GaAs
heterostructure with 71 at.% Co the magnetoresistance reaches 1000 ( %)
at room temperature. On the contrary, for SiO(Co)/Si heterostructures
magnetoresistance values are very small (4%) and for SiO(Co) films the
magnetoresistance has an opposite value. High values of the magnetoresistance
effect in SiO(Co)/GaAs heterostructures have been explained by
magnetic-field-controlled process of impact ionization in the vicinity of the
spin-dependent potential barrier formed in the semiconductor near the
interface. Kinetic energy of electrons, which pass through the barrier and
trigger the avalanche process, is reduced by the applied magnetic field. This
electron energy suppression postpones the onset of the impact ionization to
higher electric fields and results in the giant magnetoresistance. The
spin-dependent potential barrier is due to the exchange interaction between
electrons in the accumulation electron layer in the semiconductor and
-electrons of Co.Comment: 25 pages, 16 figure
ΠΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ Π±Π°ΡΡΠ΅ΡΠ½ΡΡ ΡΠ»ΠΎΠ΅Π² Π΄ΠΈΠΎΠΊΡΠΈΠ΄Π° ΡΠΈΡΠ°Π½Π° Π΄Π»Ρ ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΌΡΠ»ΡΡΠΈΡΠ΅ΡΡΠΎΠΈΠΊΠΎΠ² ΡΠ΅ΡΡΠΎΠΌΠ°Π³Π½Π΅ΡΠΈΠΊ/ΡΠ΅Π³Π½Π΅ΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΠΊ
The layered multiferroics Co/PZT were obtained by ion-beam sputtering-deposition method, where PZT is a ferroelectric ceramic based on lead titanate zirconate of the composition PbZr0.45Ti0.55O3 with a thermostable plane-parallel ferroelectric/ferromagnet interface. Using cross-sectional scanning electron microscopy (SEM), we studied the interface of a cobalt layer up to several micrometers thick with a thick ceramic substrate of lead zirconate titanate. It has been shown that the use of a titanium dioxide barrier layer of TiO2 instead of PZT allows quality improvement of the interface by reducing the duration of ion-beam planarization of the ferroelectric substrate, and also to eliminate the formation of intermediate chemical compounds. Based on the data of X-ray phase analysis (XRD), it was concluded that the TiO2 layer is amorphous. Magnetoelectric measurements have shown that the use of titanium dioxide instead of PZT under appropriate planarization modes can increase the low-frequency magnetoelectric effect to 5 mV/(cmβΠΠ΅), compared with structures with a sputtering planarizing layer of PZT, where the magnitude of the low-frequency magnetoelectric effect is 2 mV/(cmβΠe). These results allow us to improve the characteristics of these structures when used as sensitive elements in devices for formation β processing of information and magnetic field sensors based on the magnetoelectric effect.Π‘ ΠΏΠΎΠΌΠΎΡΡΡ ΠΌΠ΅ΡΠΎΠ΄Π° ΠΈΠΎΠ½Π½ΠΎ-Π»ΡΡΠ΅Π²ΠΎΠ³ΠΎ ΡΠ°ΡΠΏΡΠ»Π΅Π½ΠΈΡ β ΠΎΡΠ°ΠΆΠ΄Π΅Π½ΠΈΡ ΠΏΠΎΠ»ΡΡΠ΅Π½Ρ ΡΠ»ΠΎΠΈΡΡΡΠ΅ ΠΌΡΠ»ΡΡΠΈΡΠ΅ΡΡΠΎΠΈΠΊΠΈ Co/Π¦Π’Π‘ (Π¦Π’Π‘ β ΡΠ΅Π³Π½Π΅ΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠ°Ρ ΠΊΠ΅ΡΠ°ΠΌΠΈΠΊΠ° Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠΈΡΠΊΠΎΠ½Π°ΡΠ° ΡΠΈΡΠ°Π½Π°ΡΠ° ΡΠ²ΠΈΠ½ΡΠ° ΡΠΎΡΡΠ°Π²Π° PbZr0,45Ti0,55O3 Ρ ΡΠ΅ΡΠΌΠΎΡΡΠ°Π±ΠΈΠ»ΡΠ½ΡΠΌ ΠΏΠ»ΠΎΡΠΊΠΎΠΏΠ°ΡΠ°Π»Π»Π΅Π»ΡΠ½ΡΠΌ ΠΈΠ½ΡΠ΅ΡΡΠ΅ΠΉΡΠΎΠΌ ΡΠ΅Π³Π½Π΅ΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΠΊ/ΡΠ΅ΡΡΠΎΠΌΠ°Π³Π½Π΅ΡΠΈΠΊ), ΠΎΠ±Π»Π°Π΄Π°ΡΡΠΈΠ΅ Π²ΠΎΡΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄ΠΈΠΌΡΠΌΠΈ Π½ΠΈΠ·ΠΊΠΎΡΠ°ΡΡΠΎΡΠ½ΡΠΌΠΈ ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠ°ΠΌΠΈ ΠΏΡΠΈ ΠΊΠΎΠΌΠ½Π°ΡΠ½ΠΎΠΉ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ΅. ΠΠ΅ΡΠΎΠ΄ΠΎΠΌ ΡΠ°ΡΡΡΠΎΠ²ΠΎΠΉ ΡΠ»Π΅ΠΊΡΡΠΎΠ½Π½ΠΎΠΉ ΠΌΠΈΠΊΡΠΎΡΠΊΠΎΠΏΠΈΠΈ (Π ΠΠ) ΠΏΠΎΠΏΠ΅ΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ΅ΡΠ΅Π½ΠΈΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½Π° Π³ΡΠ°Π½ΠΈΡΠ° ΡΠ°Π·Π΄Π΅Π»Π° ΡΠ»ΠΎΡ ΠΊΠΎΠ±Π°Π»ΡΡΠ° ΡΠΎΠ»ΡΠΈΠ½ΠΎΠΉ Π΄ΠΎ Π½Π΅ΡΠΊΠΎΠ»ΡΠΊΠΈΡ
ΠΌΠΈΠΊΡΠΎΠΌΠ΅ΡΡΠΎΠ² Ρ ΡΠΎΠ»ΡΡΠΎΠΉ ΠΊΠ΅ΡΠ°ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΠΎΠ΄Π»ΠΎΠΆΠΊΠΎΠΉ ΡΠΈΡΠΊΠΎΠ½Π°ΡΠ° β ΡΠΈΡΠ°Π½Π°ΡΠ° ΡΠ²ΠΈΠ½ΡΠ°. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ Π±Π°ΡΡΠ΅ΡΠ½ΠΎΠ³ΠΎ ΡΠ»ΠΎΡ Π΄ΠΈΠΎΠΊΡΠΈΠ΄Π° ΡΠΈΡΠ°Π½Π° TiO2 Π²ΠΌΠ΅ΡΡΠΎ Π¦Π’Π‘ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ Π΄ΠΎΠ±ΠΈΡΡΡΡ ΡΠ»ΡΡΡΠ΅Π½ΠΈΡ ΠΊΠ°ΡΠ΅ΡΡΠ²Π° ΠΈΠ½ΡΠ΅ΡΡΠ΅ΠΉΡΠ° Π·Π° ΡΡΠ΅Ρ ΡΠΌΠ΅Π½ΡΡΠ΅Π½ΠΈΡ Π΄Π»ΠΈΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ ΠΈΠΎΠ½Π½ΠΎ-Π»ΡΡΠ΅Π²ΠΎΠΉ ΠΏΠ»Π°Π½Π°ΡΠΈΠ·Π°ΡΠΈΠΈ ΡΠ΅Π³Π½Π΅ΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΠΎΠ΄Π»ΠΎΠΆΠΊΠΈ, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΈΡΠΊΠ»ΡΡΠΈΡΡ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΠ΅ ΠΏΡΠΎΠΌΠ΅ΠΆΡΡΠΎΡΠ½ΡΡ
Ρ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΠΉ. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ Π΄Π°Π½Π½ΡΡ
ΡΠ΅Π½ΡΠ³Π΅Π½ΠΎΡΠ°Π·ΠΎΠ²ΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π° (Π Π€Π) ΡΠ΄Π΅Π»Π°Π½ Π²ΡΠ²ΠΎΠ΄ ΠΎΠ± Π°ΠΌΠΎΡΡΠ½ΠΎΡΡΠΈ ΡΠ»ΠΎΡ TiO2, ΠΊΠΎΡΠΎΡΡΠΉ ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΠ΅Ρ Π±ΠΎΠ»Π΅Π΅ ΡΠ°Π²Π½ΠΎΠΌΠ΅ΡΠ½ΠΎ, Π±Π΅Π· ΠΈΡΠΊΠ°ΠΆΠ΅Π½ΠΈΠΉ, ΠΏΠ΅ΡΠ΅Π΄Π°Π²Π°ΡΡ Π²Π½ΡΡΡΠ΅Π½Π½ΠΈΠ΅ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΡ, Π²ΠΎΠ·Π½ΠΈΠΊΠ°ΡΡΠΈΠ΅ ΠΌΠ΅ΠΆΠ΄Ρ ΡΠ΅Π³Π½Π΅ΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΏΠΎΠ΄Π»ΠΎΠΆΠΊΠΎΠΉ ΠΈ ΡΠ΅ΡΡΠΎΠΌΠ°Π³Π½ΠΈΡΠ½ΡΠΌ ΡΠ»ΠΎΠ΅ΠΌ. ΠΡΠΎ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ Π±ΠΎΠ»Π΅Π΅ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΠΌΡ ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΌΡ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ ΠΈ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎΠΌΡ ΠΏΠΎ Π²Π΅Π»ΠΈΡΠΈΠ½Π΅ (Π² Π΅Π΄ΠΈΠ½ΠΈΡΡ β Π΄Π΅ΡΡΡΠΊΠΈ ΠΌΠ/Π) Π½ΠΈΠ·ΠΊΠΎΡΠ°ΡΡΠΎΡΠ½ΠΎΠΌΡ ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΌΡ ΡΡΡΠ΅ΠΊΡΡ ΠΏΡΠΈ ΠΊΠΎΠΌΠ½Π°ΡΠ½ΠΎΠΉ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ΅. ΠΠ°Π³Π½ΠΈΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΈΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΡ ΠΏΠΎΠΊΠ°Π·Π°Π»ΠΈ, ΡΡΠΎ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ Π΄ΠΈΠΎΠΊΡΠΈΠ΄Π° ΡΠΈΡΠ°Π½Π° Π²ΠΌΠ΅ΡΡΠΎ Π¦Π’Π‘ ΠΏΡΠΈ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΡΡΠΈΡ
ΡΠ΅ΠΆΠΈΠΌΠ°Ρ
ΠΏΠ»Π°Π½Π°ΡΠΈΠ·Π°ΡΠΈΠΈ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΡ Π½ΠΈΠ·ΠΊΠΎΡΠ°ΡΡΠΎΡΠ½ΠΎΠ³ΠΎ ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΡΡΠ΅ΠΊΡΠ° Π΄ΠΎ 5 ΠΌΠ/(ΡΠΌ βΠ) ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ ΡΠΎ ΡΡΡΡΠΊΡΡΡΠ°ΠΌΠΈ Ρ Π½Π°ΠΏΡΠ»Π΅Π½ΠΈΠ΅ΠΌ ΠΏΠ»Π°Π½Π°ΡΠΈΠ·ΡΡΡΠ΅Π³ΠΎ ΡΠ»ΠΎΡ Π¦Π’Π‘, Π³Π΄Π΅ Π²Π΅Π»ΠΈΡΠΈΠ½Π° Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΡΡΡΠ΅ΠΊΡΠ° ΡΠΎΡΡΠ°Π²Π»ΡΠ΅Ρ 2 ΠΌΠ/(ΡΠΌ βΠ). ΠΡΠΈ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΡ ΠΏΠΎΠ·Π²ΠΎΠ»ΡΡΡ ΡΠ»ΡΡΡΠΈΡΡ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠΈ ΡΠΊΠ°Π·Π°Π½Π½ΡΡ
ΡΡΡΡΠΊΡΡΡ ΠΏΡΠΈ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠΈ Π² ΠΊΠ°ΡΠ΅ΡΡΠ²Π΅ ΡΡΠ²ΡΡΠ²ΠΈΡΠ΅Π»ΡΠ½ΡΡ
ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² Π² ΡΡΡΡΠΎΠΉΡΡΠ²Π°Ρ
ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ β ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΠΈ ΠΈΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΈ Π΄Π°ΡΡΠΈΠΊΠΎΠ² ΠΌΠ°Π³Π½ΠΈΡΠ½ΠΎΠ³ΠΎ ΠΏΠΎΠ»Ρ Π½Π° ΠΎΡΠ½ΠΎΠ²Π΅ ΠΌΠ°Π³Π½ΠΈΡΠΎΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΡΡΠ΅ΠΊΡΠ°
Ultrafast transport and relaxation of hot plasmonic electrons in metal-dielectric heterostructures
Owing to the ultrashort timescales of ballistic electron transport, relaxation dynamics of hot nonequilibrium electrons is conventionally considered local. Utilizing propagating surface plasmon-polaritons (SPs) in metal-dielectric heterostructures, we demonstrate that both local (relaxation) and nonlocal (transport) hot electron dynamics contribute to the transient optical response. The data obtained in two distinct series of pump-probe experiments demonstrate a strong increase in both nonthermal electron generation efficiency and nonlocal relaxation timescales at the SP resonance. We develop a simple kinetic model incorporating a SP excitation, where both local and nonlocal electron relaxation in metals are included, and analyze nonequilibrium electron dynamics in its entirety in the case of collective electronic excitations. Our results elucidate the role of SPs in nonequilibrium electron dynamics and demonstrate rich perspectives of ultrafast plasmonics for tailoring spatiotemporal distribution of hot electrons in metallic nanostructures
Surface Plasmon-Mediated Nanoscale Localization of Laser-Driven sub-Terahertz Spin Dynamics in Magnetic Dielectrics
We report spatial localization of the effective magnetic field generated via the inverse Faraday effect employing surface plasmon polaritons (SPPs) at Au/garnet interface. Analyzing both numerically and analytically the electric field of the SPPs at this interface, we corroborate our study with a proof-of-concept experiment showing efficient SPP-driven excitation of coherent spin precession with 0.41 THz frequency. We argue that the subdiffractional confinement of the SPP electric field enables strong spatial localization of the SPP-mediated excitation of spin dynamics. We demonstrate two orders of magnitude enhancement of the excitation efficiency at the surface plasmon resonance within a 100 nm layer of a dielectric garnet. Our findings broaden the horizons of ultrafast spin-plasmonics and open pathways toward nonthermal opto-magnetic recording on the nanoscale