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Research project in Magnetism & Spin Electronics

Research supervisor: Dr. Plamen StamenovMagnetism & Spin Electronics

Magnetic Semiconductors: p-n Junctions and Magnetic Bipolar Heterojunction Transistors

Research project in Magnetism & Spin Electronics

Magnetism & Spin ElectronicsScientific Background / Current Research

Magnetic Semiconductors are a class of materials that utilize the versatility andfunctionality of semiconductors, and take advantage of the spin degree of freedom, inorder to enable key applications in modern spin electronics (not to be confused with therather controversial class of Dilute Magnetic Semiconductors). The realisation of activeelectronic components with net spin gain is a ‘holy grail’ of spin electronics research, as itwould enable the creation of spin-based logic gates and further development ofcomponents such as non-volatile programmable logic and storage arrays, among others.Magnetic-semiconductor-based devices are one of the ways forward.

ProjectProject

The project will involve the synthesisand characterisation of bulk ferro-,ferri- and antiferromagneticsemiconducting systems (such asCuCrO :Mg and CdCr Se ) and theCuCrO2:Mg and CdCr2Se4) and thesubsequent deposition of multi-layers stacks by Pulsed LaserDeposition (see diagram on theright), in collaboration with the groupof Prof. J. Lunney, and the formationf di d d t i t t t

Schematic of the PLD tool used for thin film deposition (left) and an actual plasmaplume within the system (right).. Image courtesy of J. Alaria and M. K. O’Sullivan

The magneto-conductance of athin film of CuCrO2:Mg in high field(up to 14 T) at varioustemperatures, both below and

200

250

300

T (K) 2 5 10 50 100an

ce M

C, %

of diode and transistor structures.The devices will be characterisedusing a variety of experimentaltechniques, including the use of highmagnetic field transport, andsynchrotron and neutron radiation.

above the antiferromagnet-paramagnet transition (TN ~ 25 K).Note the very high magnitude ofthe effect (> 300 %) at lowtemperatures.

Al / Au

ZnO:Al

-14 -12 -10 -8 -6 -4 -2 0 2 4 6 8 10 12 14

0

50

100

150

150 200 250 300

Mag

neto

cond

ucta

Magnetic Field 0H, T

Schematic structure of themagnetic bipolar heteroj nction

Funding

Funding for this project has been approved and is available through the School of Physics and CRANN, TCD. Contact detailst l @t d i R SNIAM 0 08 t l 353 1 896 2171

Al2O3

CuCrO2:Mgmagnetic bipolar heterojunctiontransistors prepared by PLDwith the use of in-situ shadowmasking.

© School of Physics, TCD, 2011

[email protected] Room no.: SNIAM 0.08 tel. +353 1 896 2171

More information / References• M. E. Flatté, Z. G. Yu, E. J-Halperin and D. D. Awschalom, Appl. Phys. Lett. 82, 4740 (2003).• J. Fabian,I. Zutić, and S. Das Sarma, Phys. Rev. B. 66, 165301 (2002).• http://www.tcd.ie/Physics/People/Plamen.Stamenov