Galvanomagnetic Effects in Oriented Single Crystals ofn-Type Germanium

Abstract

Measurements of the magnetoresistance, Hall, and planar Hall coefficients have been made on oriented single crystals of w-type germanium at 77° and 300°K. At 77 °K measurements made as a function of the magnetic field strength and of the angle between the current and the magnetic field are found to be in agreement with theoretical calculations based on an energy-independent mean free time TO which has the same form of anisotropy as the effective mass at the bottom of the conduction band. The value of ro is determined from previously described Hall measurements and the anisotropy factor K is determined from the high-field longitudinal magnetoresistance. K decreases from about 16 to about 12 or 13 as the electron density increases from about 5.4 X10 13 cm" 3 to about 5.2 X10 14 cm" 3 .At 300 °K measurements were made for selected orientations of current and field on samples whose resistivities varied from 0.016 to 8.9 ohm-cm. The usual low-field symmetry relations are

Shape-induced bi-stable magnetic states in submicrometer structures of permalloy films

“…[1][2][3][4] Here we use nanolithography to induce effective bi-axial magnetic anisotropy and discuss the potential relevance of such structures for magnetic random access memory (MRAM) based on the planar Hall effect (PHE). [5][6][7] Currently developed MRAM is widely based on magnetoresistance tunnel junctions (MTJ) 8,9 consisting of two ferromagnetic layers separated by a thin insulating layer. The two memory states of the MTJ are related to its two resistance states, which correspond to parallel and antiparallel alignment of the magnetization in the two ferromagnetic layers.…”

Perspective of Spintronics Applications Based on the Extraordinary Hall Effect

“…2 Anisotropic magnetoresistance [1,2], planar Hall effect [3,4], spin-dependent tunneling [5,6] and the extraordinary or anomalous Hall effect (EHE) [7,8] are spin-dependent electronic transport phenomena known for many years. However, it is the discovery of the giant magnetoresistance (GMR) [9,10] that gave birth to the term spintronics and triggered a world-wide outburst of the spin-related research.…”

“…The other scattering mechanism, so-called side jump [19], is quantum in nature and results in a constant lateral displacement of the charge trajectory at the point of scattering. For the side jump process 2 ρ ∝ EHE R , and this mechanism is expected to dominate in highly resistive samples at elevated temperatures 4 or with high degree of doping. In general, experimental data does not fit well the predictions of the models.…”

“…Already achieved sensitivity of the EHE-based sample devices exceeds 1000 Ω/T, which surpasses the sensitivity of semiconducting Hall sensors. Linear field response, thermal stability, high frequency operation, sub-micron dimensions and, above all, simplicity, robustness and low cost manufacture are good reasons to consider a wide scale technological application of the phenomenon for magnetic sensors and memory devices.2 Anisotropic magnetoresistance [1,2], planar Hall effect [3,4], spin-dependent tunneling [5,6] and the extraordinary or anomalous Hall effect (EHE) [7,8] are spin-dependent electronic transport phenomena known for many years. However, it is the discovery of the giant magnetoresistance (GMR) [9,10] that gave birth to the term spintronics and triggered a world-wide outburst of the spin-related research.…”

Magnetoresistance of High‐Ohmic Semiconductors by a Capacitive Method

“…The measurements could be made f o r t h e t r a n s v e r s e and t h e l o n g i t u d i n a l e f f e c t s (and f o r o r i e n t a t i o n s i n between) at temperatures between 60 and 295 OK. The c r y s t a l s were c i r c u l a r d i s k s of 1 mm t h i c k n e s s and 8 mm diameter; t h e i r s u r f a c e w a s perpendicular t o t h e [ I l l ] d i r e c t i o n .The r e s u l t s of the measurements w i t h Ge (n-type, donor c o n c e n t r a t i o n about 1 .5x101 ~m -~) agreed w e l l w i t h previous r e s u l t s f r o m current-voltage c h a r a c t e r i s t i c s methods ( 2 ) f o r t h e so-called "physical e f f e c t " (change o f m o b i l i t i e s i n t h e magnetic f i e l d ) i n s p i t e o f a geometry of t h e sample that would provoke a llgeometrical e f f e c t " (3). W e shall d i s c u s s t h i s circumstance i n a more d e t a i l e d r e p o r t t o be published l a t e r .…”