Structural engineering of ferromagnetism in III–V digital ferromagnetic heterostructures

Schuller, J. A.; Johnston-Halperin, Ezekiel; Gallinat, Chad S.; Knotz, H.; Gossard, A. C.; Awschalom, D. D.

doi:10.1063/1.1667594

Cited by 5 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is consistent with the inverse magnetoelastic effect, but the magnetoelastic coupling parameters that quantify this behavior have remained elusive. These parameters are important in gauging the impact of magnetostriction on magnetic [3] and electrical transport properties [4,5], and are therefore essential to a comprehensive understanding of DMS systems. Here, we demonstrate a scheme to observe magnetostriction directly in a resonant nanoelectromechanical system (NEMS).…”

mentioning

confidence: 99%

Nanomechanical Measurement of Magnetostriction and Magnetic Anisotropy in (Ga,Mn)As

et al. 2005

View full text Add to dashboard Cite

A GaMnAs nanoelectromechanical resonator is used to obtain the first measurement of magnetostriction in a dilute magnetic semiconductor. Resonance frequency shifts induced by field-dependent magnetoelastic stress are used to simultaneously map the magnetostriction and magnetic anisotropy constants over a wide range of temperatures. Owing to the central role of carriers in controlling ferromagnetic interactions in this material, the results appear to provide insight into a unique form of magnetoelastic behavior mediated by holes. DOI: 10.1103/PhysRevLett.95.187206 PACS numbers: 75.80.+q, 75.50.Pp, 75.70.ÿi, 85.85.+j The dilute magnetic semiconductor (DMS) GaMnAs has been extensively studied for its promising spintronics applications [1,2]. Among its properties is the dominant role of growth-induced strain upon the material's magnetic alignment. A change from compressive to tensile strain is known to flip the moments from in plane to out of plane [1]. This is consistent with the inverse magnetoelastic effect, but the magnetoelastic coupling parameters that quantify this behavior have remained elusive. These parameters are important in gauging the impact of magnetostriction on magnetic [3] and electrical transport properties [4,5], and are therefore essential to a comprehensive understanding of DMS systems. Here, we demonstrate a scheme to observe magnetostriction directly in a resonant nanoelectromechanical system (NEMS). Similarities between the piezoresistive, piezoelectric, and elastic properties of GaMnAs to conventionally doped GaAs enable straightforward electromechanical actuation and transduction [6,7] of a doubly clamped beam resonator. Mechanical resonance frequency variations occur as the device is stretched or compressed magnetoelastically in an applied magnetic field, providing a measure of magnetostriction with an accuracy comparable to other methods [8,9]. Furthermore, the angular dependence of the observed magnetostriction enables measurement of another important property, magnetic anisotropy.The material is grown epitaxially on an (001) GaAs substrate, beginning with a 1 m Al 0:8 Ga 0:2 As sacrificial layer, followed by 50 nm high temperature and 50 nm low temperature GaAs, and finally 80 nm unannealed Ga 0:948 Mn 0:052 As with a Curie temperature of 57 K. The spontaneous magnetization is expected to lie in the growth plane due to a compressive strain from the substrate and demagnetization effects. Electron beam lithography is used to define the device profile, which is subsequently covered with a titanium etch mask. Next, argon ion milling removes all magnetic material not protected by the mask. A 30 nm-thick gold side gate is deposited 0:7 m away from the beam after another lithography step. Finally, a rectangular resist window is patterned to expose the sacrificial layer, which is selectively removed along with the remaining titanium mask in dilute hydrofluoric acid. The resulting suspended structure, shown in the inset of Fig. 1(a), has dimensions of L; w; t 6; 0:5; 0:18 m, with its longit...

show abstract

mentioning

confidence: 99%

Nanomechanical Measurement of Magnetostriction and Magnetic Anisotropy in (Ga,Mn)As

et al. 2005

View full text Add to dashboard Cite

show abstract

“…MRAM can be made from a half metallic superlattice arrangement of digital ferromagnetic heterostructure (DFH). 18 A DFH is a semiconductor, such as GaAs or Si, δ-doped with a layer of a transition metal element. Half metals can also be used for polarized light sources and optoelectronic devices.…”

Section: Introductionmentioning

confidence: 99%

Design of Spintronic Materials with Simple Structures

Garai

Nandi²

2008

j nanosci nanotechnol

View full text Add to dashboard Cite

The melt rheology of polyaniline (PANI)-dinonylnaphthalenedisulfonic acid (DNNDSA) gel nanocomposites (GNCs) with organically modified (modified with cetyl trimethylammonium bromide)-montmorillonite (om-MMT) clay has been studied for three different clay concentrations at the temperature range 120-160 degrees C. Field emission scanning electron microscopy (FE-SEM), wide angle X-ray scattering (WAXS), differential scanning calorimetry (DSC) and dc-conductivity data (approximately 10(-3) S/cm) indicate that the PANI-DNNDSA melt is in sol state and it is not de-doped at that condition. The WAXS data indicate that in GNC-1 sol clay tactoids are in exfoliated state but in the other sols they are in intercalated state. The zero shear viscosity (eta0), storage modulus (G') and loss modulus (G") increase than that of pure gel in the GNCs. The pure sol and the sols of gel nanocomposites (GNCs) exhibit Newtonian behavior for low shear rate (< 6 x 10(-3) s(-1)) and power law variation for the higher shear rate region. The characteristic time (A) increase with increasing clay concentration and the power law index (n) decreases with increase in clay concentration in the GNCs indicating increased shear thinning for the clay addition. Thus the sols of om-clay nanocomposites of PANI-DNNDSA system are easily processible. The storage modulus (G') of GNC sols are higher than that of pure PANI-DNNDSA sol, GNC1 sol shows a maximum of 733% increase in storage modulus and the percent increase decreases with increase in temperature. Exfoliated nature of clay tactoids has been attributed for the above dramatic increase of G'. The PANI-DNNDSA sol nanocomposites behave as a pseudo-solid at higher frequency where G' and loss modulus (G") show a crossover point in the frequency sweep experiment at a fixed temperature. The crossover frequency decreases with increase in clay concentration and it increases with increase in temperature for GNC sols. The pseudo-solid behavior has been explained from jamming or network formation of clay tactoids under shear. A probable explanation of the two apparently contradictory phenomena of shear thinning versus pseudo-solid behavior of the nanocomposite sols is discussed.

show abstract

“…Therefore, half metals are ideal candidates for MR based devices: information storage, spin filters, detectors, sensors, and the like. MRAM can be made from a half metallic superlattice arrangement of digital ferromagnetic heterostructure (DFH) 18. A DFH is a semiconductor, such as GaAs or Si, δ-doped with a layer of a transition metal element.…”

mentioning

confidence: 99%

Design of Spintronic Materials with Simple Structures

Fong¹,

Qian²,

Li³

et al. 2008

j nanosci nanotechnol

View full text Add to dashboard Cite

A brief comparison of conventional electronics and spintronics is given. The key features of half metallic binary compounds with the zincblende structure are presented, using MnAs as an example. We discuss the interactions responsible for the half metallic properties. Special properties of superlattices and a digital ferromagnetic heterostructure incorporating zincblende half metals are also discussed.

show abstract

Structural engineering of ferromagnetism in III–V digital ferromagnetic heterostructures

Cited by 5 publications

References 11 publications

Nanomechanical Measurement of Magnetostriction and Magnetic Anisotropy in (Ga,Mn)As

Nanomechanical Measurement of Magnetostriction and Magnetic Anisotropy in (Ga,Mn)As

Design of Spintronic Materials with Simple Structures

Design of Spintronic Materials with Simple Structures

Contact Info

Product

Resources

About