Large Perpendicular Exchange Energy in TbxCo100−x/Cu(t)/[Co/Pt]2 Heterostructures

In order to realize a perpendicular exchange bias for applications, a robust and tunable exchange bias is required for spintronic applications. Here, we show the perpendicular exchange energy (PEE) in the TbxCo100−x/Cu/[Co/Pt]2 heterostructures. The structure consists of amorphous ferrimagnetic Tb–Co alloy films and ferromagnetic Co/Pt multilayers. The dependence of the PEE on the interlayer thickness of Cu and the composition of Tb–Co were analyzed. We demonstrate that the PEE can be controlled by changing the Cu interlayer thickness of 0.2 < tCu < 0.3 (nm). We found that PEE reaches a maximum value (σPw = 1 erg/cm2) at around x = 24%. We, therefore, realize the mechanism of PEE in the TbxCo100−x/Cu/[Co/Pt]2 heterostructures. We observe two competing mechanisms—one leading to an increase and the other to a decrease—which corresponds to the effect of Tb content on saturation magnetization and the coercivity of heterostructures. Sequentially, our findings show possibilities for both pinned layers in spintronics and memory device applications by producing large PEE and controlled PEE by Cu thickness, based on TbxCo100−x/Cu/[Co/Pt]2 heterostructures.

Download Full-text

Hysteresis Behavior of the Donor–Acceptor-Type Ambipolar Semiconductor for Non-Volatile Memory Applications

Micromachines ◽

10.3390/mi12030301 ◽

2021 ◽

Vol 12 (3) ◽

pp. 301

Author(s):

Young Jin Choi ◽

Jihyun Kim ◽

Min Je Kim ◽

Hwa Sook Ryu ◽

Han Young Woo ◽

...

Keyword(s):

Organic Semiconductor ◽

Field Effect ◽

Field Effect Transistor ◽

Memory Device ◽

Non Volatile Memory ◽

Device Applications ◽

Donor Acceptor ◽

Effect Transistor ◽

Volatile Memory ◽

Memory Applications

Donor–acceptor-type organic semiconductor molecules are of great interest for potential organic field-effect transistor applications with ambipolar characteristics and non-volatile memory applications. Here, we synthesized an organic semiconductor, PDPPT-TT, and directly utilized it in both field-effect transistor and non-volatile memory applications. As-synthesized PDPPT-TT was simply spin-coated on a substrate for the device fabrications. The PDPPT-TT based field-effect transistor showed ambipolar electrical transfer characteristics. Furthermore, a gold nanoparticle-embedded dielectric layer was used as a charge trapping layer for the non-volatile memory device applications. The non-volatile memory device showed clear memory window formation as applied gate voltage increases, and electrical stability was evaluated by performing retention and cycling tests. In summary, we demonstrate that a donor–acceptor-type organic semiconductor molecule shows great potential for ambipolar field-effect transistors and non-volatile memory device applications as an important class of materials.

Download Full-text

Structural and magnetic study of metallo-organic YIG powder using 2-ethylhexanoate carboxylate-based precursors

Modern Physics Letters B ◽

10.1142/s0217984919501008 ◽

2019 ◽

Vol 33 (09) ◽

pp. 1950100 ◽

Cited By ~ 1

Author(s):

S. Hosseinzadeh ◽

P. Elahi ◽

M. Behboudnia ◽

M. H. Sheikhi ◽

S. M. Mohseni

Keyword(s):

Saturation Magnetization ◽

Annealing Temperature ◽

Sintering Temperature ◽

Magnetic Behavior ◽

Yttrium Iron ◽

Organic Precursor ◽

Maximum Value ◽

Diffraction Peaks ◽

Iron Garnet ◽

Organic Decomposition

The crystallization and magnetic behavior of yttrium iron garnet (YIG) prepared by metallo-organic decomposition (MOD) method are discussed. The chemistry and physics related to synthesis of iron and yttrium carboxylates based on 2-ethylhexanoic acid (2EHA) are studied, since no literature was found which elucidates synthesis of metallo-organic precursor of YIG in spite of the literatures of doped YIG samples such as Bi-YIG. Typically, the metal carboxylates used in preparation of ceramic oxide materials are 2-ethylhexanoate (2EH) solvents. Herein, the synthesis, thermal behavior and solubility of yttrium and iron 2EH used in synthesis of YIG powder by MOD are reported. The crystallization and magnetic parameters, including saturation magnetization and coercivity of these samples, smoothly change as a function of the annealing temperature. It is observed that high sintering temperature of [Formula: see text] to [Formula: see text] promotes the diffraction peaks of YIG, therefore, we can conclude that the formation of YIG in MOD method increases the crystallization temperature. The maximum value of saturation magnetization and minimum value of coercivity and remanence are observed for the sample sintered at [Formula: see text] which are 13.7 emu/g, 10.38 Oe and 1.5 emu/g, respectively. This study cites the drawbacks in chemical synthesis of metallo-organic-based YIG production.

Download Full-text

Magnetocrystalline Anisotropy and Twinning Stress of 10M and 2M Martensites in Ni-Mn-Ga System

Materials Science Forum ◽

10.4028/www.scientific.net/msf.512.195 ◽

2006 ◽

Vol 512 ◽

pp. 195-200 ◽

Cited By ~ 2

Author(s):

Nariaki Okamoto ◽

Takashi Fukuda ◽

Tomoyuki Kakeshita ◽

Tetsuya Takeuchi

Keyword(s):

Magnetic Field ◽

Shear Stress ◽

Magnetocrystalline Anisotropy ◽

Anisotropy Constant ◽

The Other ◽

Magnetic Shear ◽

Maximum Value ◽

Twinning Plane ◽

Twinning Shear ◽

The Difference

Ni2MnGa alloy with 10M martensite exhibits rearrangement of martensite variants (RMV) by magnetic field, but Ni2.14Mn0.92Ga0.94 with 2M martensite does not. In order to explain the difference, we measured uniaxial magnetocrystalline anisotropy constant Ku and the stress required for twinning plane movement τreq in these alloys. Concerning the former alloy, the maximum value of magnetic shear stress acting across twinning plane τmag, which is evaluated as |Ku| divided by twinning shear, becomes larger than τr eq. On the other hand, concerning the latter alloy, the maximum of τmag is only one-tenth of τreq at any temperature examined. Obviously, the relation, τmag> τr eq, is satisfied when RMV occurs by magnetic field and vice versa. In this martensite, the large twinning shear of 2M martensite is responsible for small τmag and large τreq.

Download Full-text

MOS structures containing silicon nanoparticles for memory device applications

Journal of Physics Conference Series ◽

10.1088/1742-6596/113/1/012034 ◽

2008 ◽

Vol 113 ◽

pp. 012034 ◽

Cited By ~ 6

Author(s):

N Nedev ◽

D Nesheva ◽

E Manolov ◽

R Brüggemann ◽

S Meier ◽

...

Keyword(s):

Silicon Nanoparticles ◽

Memory Device ◽

Device Applications ◽

Mos Structures

Download Full-text

Triple high k stacks (AI/sub 2/O/sub 3//HfO/sub 2//AI/sub 2/O/sub 3/) with high pressure (10atm) H/sub 2/and D/sub 2/ annealing for SONOS type flash memory device applications

4th IEEE Conference on Nanotechnology, 2004. ◽

10.1109/nano.2004.1392247 ◽

2005 ◽

Cited By ~ 3

Author(s):

Sanghun Jeon ◽

Sangmoo Choi ◽

Hokyung Park ◽

Hyunsang Hwang ◽

Jung Hee Han ◽

...

Keyword(s):

High Pressure ◽

Flash Memory ◽

Memory Device ◽

High K ◽

Device Applications

Download Full-text

Nd doped lead titanate crystals for microelectronic memory device applications

Journal of Materials Science Materials in Electronics ◽

10.1007/s10854-016-4725-9 ◽

2016 ◽

Vol 27 (7) ◽

pp. 7478-7486

Author(s):

Mitesh Chakraborty ◽

Swarat Chaudhuri ◽

Vineet Kumar Rai ◽

Vishal Mishra

Keyword(s):

Lead Titanate ◽

Memory Device ◽

Device Applications

Download Full-text

A.C conductivity and dielectric properties of (PVA/ PEO) blends doped with MWCNTs

Iraqi Journal of Physics (IJP) ◽

10.30723/ijp.v14i30.201 ◽

2019 ◽

Vol 14 (30) ◽

pp. 64-72

Author(s):

Ahmad A. Hasan

Keyword(s):

Electrical Conductivity ◽

Dielectric Properties ◽

The Other ◽

Poly Vinyl Alcohol ◽

Conductivity Measurements ◽

Frequency Range ◽

Maximum Value ◽

Multi Walled Carbon Nanotube ◽

Poly Ethylene Oxide ◽

Poly Ethylene

A.C electrical conductivity and dielectric properties for poly(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undopedand doped with multi-walled carbon nanotube (MWCNTs) withdifferent concentrations (1, and 3 wt %) in the frequency range(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)blends undoped and doped with MWCNTs were prepared usingcasting technique. The electrical conductivity measurements showedthat σA.C is frequency dependent and obey the relation σA.C =Aωs forundoped and doped blends with 1% MWCNTs, while it is frequencyindependent with increases of MWCNTs content to 3%. Theexponent s showed proceeding increase with the increase of PEOratio (≥50%) for undoped blends samples, while s value for dopedblends exhibits to change in different manner, i.e. s increases andreach maximum value at 50/50 PVA/PEO, then decreases forresidual doped blends samples with 1% MWCNTs on the other handthe exponent s decrease and reach minimum value at 50/50PVA/PEO for samples doped with 3% MWCNTs, then return toincrease. The results explained in different terms.

Download Full-text

Effect of vacuum annealing on evaporated pentacene thin films for memory device applications

Materials Science and Engineering B ◽

10.1016/j.mseb.2016.06.009 ◽

2016 ◽

Vol 211 ◽

pp. 110-114 ◽

Cited By ~ 2

Author(s):

A.G. Gayathri ◽

C.M. Joseph

Keyword(s):

Thin Films ◽

Vacuum Annealing ◽

Memory Device ◽

Device Applications

Download Full-text

Effect of ultra-thin Cu underlayer on the magnetic properties of Ni80Fe50 / Fe50Mn50 films

MRS Proceedings ◽

10.1557/proc-562-69 ◽

1999 ◽

Vol 562 ◽

Author(s):

C. Liu ◽

L. Shen ◽

H. Jiang ◽

D. Yang ◽

G. Wu ◽

...

Keyword(s):

Thin Film ◽

Atomic Force Microscopy ◽

Exchange Bias ◽

Film Material ◽

X Ray Diffraction ◽

X Ray ◽

Force Microscopy ◽

Atomic Force ◽

Maximum Value ◽

Film Roughness

ABSTRACTThe Ni80Fe20/Fe50Mn50,thin film system exhibits exchange bias behavior. Here a systematic study of the effect of atomic-scale thin film roughness on coercivity and exchange bias is presented. Cu (t) / Ta (100 Å) / Ni80Fe20 (100 Å) / Fe50Mno50 (200 Å) / Ta (200 Å) with variable thickness, t, of the Cu underlayer were DC sputtered on Si (100) substrates. The Cu underlayer defines the initial roughness that is transferred to the film material since the film grows conformal to the initial morphology. Atomic Force Microscopy and X-ray diffraction were used to study the morphology and texture of the films. Morphological characterization is then correlated with magnetometer measurements. Atomic Force Microscopy shows that the root mean square value of the film roughness exhibits a maximum of 2.5 Å at t = 2.4 Å. X-ray diffraction spectra show the films are polycrystalline with fcc (111) texture and the Fe50Mn50 (111) peak intensity decreases monotonically with increasing Cu thickness, t. Without a Cu underlayer, the values of the coercivity and loop shift are, Hc = 12 Oe and Hp = 56 Oe, respectively. Both the coercivity and loop shift change with Cu underlayer thickness. The coercivity reaches a maximum value of Hc= 36 Oe at t = 4 Å. The loop shift exhibits an initial increase with t, reaches a maximum value of HP = 107 Oe at t = 2.4 Å, followed by a decrease with greater Cu thickness. These results show that a tiny increase in the film roughness has a huge effect on the exchange bias magnitude.

Download Full-text