Abstract
Exchange-coupled interfacial structures of Fe/NiO and NiO/Fe with pSi substrate have been studied and also the effect of swift heavy ion irradiation on the morphological, structural, transport and magnetic behaviour is reported. The interfacial structures have been characterised from X-ray diffraction (XRD), magnetic force microscopy/atomic force microscopy, X-ray photoelectron spectroscopy and magnetisation characteristics. XRD and X-ray photoelectron spectroscopy studies have shown the formation of various silicide and oxide phases due to the interfacial intermixing across the interfaces which is found to affect the transport and magnetic behaviour. A significant enhancement in exchange bias field and coercivity has been observed for Fe/NiO/pSi interfacial structure on the irradiation (as compared to unirradiated ones). The observed enhanced exchange bias and coercivity on the irradiation has been understood due to creation of uncompensated surface/pinned interfacial spins. Magnetic field-induced enhanced current has been observed at low temperatures (50–250 K) for the irradiated structure suggesting the spin-mixing effect. Low temperature magneto-transport study across the irradiated interface has shown negative magnetoresistance (MR) as compared to unirradiated ones for which positive MR is observed. The observed change in MR at low temperatures has been understood in terms of diffuse scattering at grain boundaries/spin-disorder scattering and/or magnetic polarons. Role of interfacial modification/changes in chemical environment across the interfaces is invoked for the observed changes in magnetic and transport behaviour of the structures. A possible explanation for the observed changes is given.
Similar content being viewed by others
References
Nogués J, Schuller IK (1999) Exchange bias. J Magn Magn Mater 192:203–232
Nogués J, Sort J, Langlais V, Skumryev V, Surinach S, Munoz JS, Baro MD (2005) Exchange bias in nanostructures. Phys Rep 422:65–117
Meiklejohn WH, Bean CP (1956) New magnetic anisotropy. Phys Rev 102:1413–1414
Mauri D, Siegmann HC, Bagus PS, Kay E (1987) Simple model for thin ferromagnetic films exchange coupled to an antiferromagnetic substrate. J Appl Phys 62:3047–3049
Malozemoff AP (1988) Mechanisms of exchange anisotropy (invited). J Appl Phys 63:3874–3879
Koon NC (1997) Calculations of exchange bias in thin films with ferromagnetic/antiferromagnetic interfaces. Phys Rev Lett 78:4865–4868
Schulthess TC, Butler WH (1998) Consequences of spin-flop coupling in exchange biased films. Phys Rev Lett 81:4516–4519
Néel L (1967) Ferro-antiferromagnetic coupling in thin layers. Ann Phys (Paris) 2:61–80
Fassbender J, Ravelosona D, Samson Y (2004) Tailoring magnetism by light-ion irradiation. J Phys D Appl Phys 37:R179–R196
Daalderop GH, Kelly PJ, den Broeder FJA (1992) Prediction and confirmation of perpendicular magnetic anisotropy in Co/Ni multilayers. Phys Rev Lett 68:682–685
Prados C, Dimitrov DV, Hadjipanayis GC, Hernando A (1998) Effect of Co impurity layers on the AMR enhancement of Ni thin films. J Magn Magn Mater 177–181:1293–1295
Wang ZG, Dufour C, Paumier E, Toulemonde M (1994) The Se sensitivity of metals under swift heavy-ion-irradiation: A transient thermal process. J Phys Condens Matter 6:6733–6750
Ziegler JF, Biersack JP, Littmark U (2008) The stopping and range of ions in matter. Pergamon Press, New York
Thomas S, Thomas H, Avasthi DK, Tripathi A, Ramanujan RV, Anantharaman MR (2009) Swift heavy ion induced surface modification for tailoring coercivity in Fe–Ni based amorphous thin films. J Appl Phys 105:033910-1–033910-7
Kerr E, van Dijken S, Langford RM, Coey JMD (2005) Effects of Ga+ ion implantation on the magnetoresistive properties of spin valves. J Magn Magn Mater 290–291:124–126
McGrouther D, Chapman JN, Vanhelmont FWM (2004) Effect of Ga+ ion irradiation on the structural and magnetic properties of CoFe/IrMn exchange biased bilayers. J Appl Phys 95:7772–7778
Wang YG, McGrouther D, McVitie S, Mackenzie M, Chapman JN (2006) Investigation of the origin of the decrease in exchange biasing in Ga+ ion irradiated CoFe/IrMn films. J Appl Phys 100:073901-1–073901-7
Schafer D, Grande PL, Pereira LG, Geshev J (2011) Ion irradiation effects on the exchange bias in IrMn/Co films. J Appl Phys 109:023905-1–023905-4
Mougin A, Mewes T, Jung M, Engel D, Ehresmann A, Schmoranzer H, Fassbender J, Hillebrands B (2001) Local manipulation and reversal of the exchange bias field by ion irradiation in FeNi/FeMn double layers. Phys Rev B 63:060409-1–060409-4
Chappert C, Bernas H, Ferré J, Kottler V, Jamet JP, Chen Y, Cambril E, Devolder T, Rousseaux F, Mathet V, Launois H (1998) Planar patterned magnetic media obtained by ion irradiation. Science 280:1919–1922
Devolder T, Chappert C, Chen Y, Cambril E, Bernas H, Jamet JP, Ferré J (1999) Sub-50 nm planar magnetic nanostructures fabricated by ion irradiation. Appl Phys Lett 74:3383–3385
Aign T, Meyer P, Lemerle S, Jamet JP, Ferré J, Mathet V, Chappert C, Gierak J, Vieu C, Rosseaux F, Launois H, Bernas H (1998) Magnetization reversal in arrays of perpendicularly magnetized ultrathin dots coupled by dipolar interaction. Phys Rev Lett 81:5656–5659
Ravelosona D, Chappert C, Mathet V, Bernas H (2000) Chemical order induced by ion irradiation in FePt (001) films. Appl Phys Lett 76:236–238
Yang CH, Lai CH, Mao S (2003) Reversing exchange fields in CoFe/PtMn and CoFe/IrMn bilayers by carbon field irradiation. J Appl Phys 93:6596–6598
Lai CH, Yang CH, Huang RT, Chen CW, Chen FR, Kai JJ, Niu H (2002) Effects of structure and ion irradiation on the exchange field of NiFe/NiMn. J Magn Magn Mater 239:390–395
Kelly DM, Schuller IK, Korenivski V, Rao KV, Larsen KK, Bottiger J, Gyorgy EM, van Dover RB (1994) Increases in giant magnetoresistance by ion irradiation. Phys Rev B 50:3481–3484
Lin JG, Wu MR, Ngu DH, Huang CY, Mao S (2000) Effect of ion-irradiation on the NiFe/Cu/NiFe/NiMn spin valve. J Magn Magn Mater 209:128–130
Kac M, Zukrowski J, Toulemonde M, Kruk R, Tokman V, Polit A, Zabila Y, Dobrowolska A, Synashenko A, Marszalek M (2009) Swift iodine ion modification of the structural and magnetotransport properties of Fe/Cr systems. Nucl Instrum Methods Phys Res B 267:925–930
Markna JH, Parmar RN, Rana DS, Kumar R, Misra P, Kukreja LM, Kuberkar DG, Malik SK (2007) Effects of swift heavy ion irradiation on La0.5Pr0.2Sr0.3MnO3 epitaxial thin films grown by pulsed laser deposition. Nucl Instrum Methods Phys Res B 256:693–697
Conraux Y, Nozieres JP, Da Costa V, Toulemonde M, Ounadjela K (2003) Effects of swift heavy ion bombardment on magnetic tunnel junction functional properties. J Appl Phys 93:7301–7303
Srivastava N, Srivastava PC (2012) A study on exchange coupled structures of Fe/NiO and NiO/Fe interfaced with n- and p-silicon substrates. J Appl Phys 111:123909-1–123909-9
Srivastava PC, Ganesan V, Sinha OP (2004) Evidence of plastic flow and recrystallization phenomena in swift (similar to 100 MeV) Si7+ ion irradiated silicon. Nucl Instrum Methods Phys Res B 222:491–496
Pedreschi F, Sturm JM, O’Mahony JD, Flipse CFJ (2003) Magnetic force microscopy and simulations of colloidal iron nanoparticles. J Appl Phys 94:3446–3450
Kaoumi D, Motta AT, Birtcher RC (2008) A thermal spike model of grain growth under irradiation. J Appl Phys 104:073525-1–073525-13
Ohldag H, Scholl A, Nolting F, Arenholz E, Maat S, Young AT, Carey M, Stohr J (2003) Correlation between exchange bias and pinned interfacial spins. Phys Rev Lett 91:017203-1–017203-4
Barbieri A, Weiss W, Van Hove MA, Somorjai GA (1994) Magnetite Fe3O4(111): surface structure by LEED crystallography and energetic. Surf Sci 302:259–279
Yu GH, Zeng LR, Zhu FW, Chai CL, Lai WY (2001) Magnetic properties and X-ray photoelectron spectroscopy study of NiO/NiFe films prepared by magnetron sputtering. J Appl Phys 90:4039–4043
Chen X, Zhao A, Shao Z, Li C, Williams CT, Liang C (2010) Synthesis and catalytic properties for phenylacetylene hydrogenation of silicide modified nickel catalysts. J Phys Chem C 114:16525–16533
Maillard-Schaller E, Boyanov BI, English S, Nemanich RJ (1999) Role of the substrate strain in the sheet resistance stability of NiSi deposited on Si(100). J Appl Phys 85:3614–3618
Sinha OP, Shripathi T, Lalla NP, Srivastava PC (2004) Electrical and XPS studies of 100 MeV Si7+ ion irradiated Pd/n-GaAs devices. Appl Surf Sci 230:222–231
Gill K, Hall G, Macevoy BC (1996) IL Nuovo Cimento. Presented at the II international conference on large-scale applications and radiation hardness of semiconductor detectors, June 28–30, 1995, Florence, vol. 109, pp. 1371–1377
Fert A, Bruno P (2005) Ultrathin magnetic structures II. In: Heinrich B, Bland JAC (eds) Interlayer coupling and magnetoresistance in multilayers. Springer, Berlin, pp 82–190
Yuan L, Ovchenkov Y, Sokolov A, Yang CS, Doudin B, Liou SH (2003) Magnetotransport properties of CrO2 films down to single-grain sizes. J Appl Phys 93:6850–6852
Acknowledgements
The authors would like to acknowledge the help received from Pelletron group, Inter University Accelerator Centre (IUAC), New Delhi, India during the irradiation experiments. The authors are thankful to Dr. D. K. Avasthi and Dr. D. Kabiraj for their involvement during irradiation experiments and Dr. Indra Sulania, Scientist (IUAC, New Delhi, India) for performing MFM/AFM measurements. The authors are also thankful to Dr. T. Shripathi (Scientist ‘H’, UGC-DAE-CSR, Indore, India) for providing the access to XPS measurement and related fruitful discussions. One of the authors (N. Srivastava) is grateful to Council of Scientific and Industrial Research (CSIR), New Delhi, India for providing the financial support in the form of Senior Research Fellowship (CSIR-SRF).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Srivastava, N., Srivastava, P.C. Heavy ion induced modifications on morphological, magnetic and magneto-transport behaviour of exchange-biased Fe/NiO and NiO/Fe bilayers with Si substrate for spintronic applications. J Mater Sci 50, 7610–7626 (2015). https://doi.org/10.1007/s10853-015-9321-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10853-015-9321-5