@article{beb3ed34f0824d63a320b634979f545e,
title = "Structure and magnetism of Co2Ge nanoparticles",
abstract = "The structural and magnetic properties of Co2Ge nanoparticles (NPs) prepared by the cluster-beam deposition (CBD) technique have been investigated. As-made particles with an average size of 5.5 nm exhibit a mixture of hexagonal and orthorhombic crystal structures. Thermomagnetic measurements showed that the as-made particles are superparamagnetic at room temperature with a blocking temperature (TB) of 20 K. When the particles are annealed at 823 K for 12 h, their size is increased to 13 nm and they develop a new orthorhombic crystal structure, with a Curie temperature (TC) of 815 K. This is drastically different from bulk, which are ferromagnetic at cryogenic temperatures only. X-ray diffraction (XRD) measurements suggest the formation of a new Co-rich orthorhombic phase (OP) with slightly increased c/a ratio in the annealed particles and this is believed to be the reason for the drastic change in their magnetic properties.",
keywords = "Cluster deposition, Curie temperature, Magnetic nanoparticles, Magnetocrystalline anisotropy",
author = "Onur Tosun and Abel, {Frank M.} and Balamurugan Balasubramanian and Ralph Skomski and Sellmyer, {David J.} and Hadjipanayis, {George C.}",
note = "Funding Information: found interesting magnetic properties, which were drastically different from bulk. Unlike bulk Co2Ge, the aIsn-m suadmemCaor2yG, we en asnyonpthaerstiiczleeds Cwoe2rGees unpaenroppaarratmiclaegsn wetiitch atthreo oormthtoermhopmerbaitcucrreydstuael stotruthcetuirresm anadll pfoaurtnicdl einsitzeer.esHtionwg emvear,gtnheetiacnpneroalpeedrtnieasn,owpahritcichl ews wereeredfrearsrtoicmaallgyn edtiifcfewreitnht afrhoimgh bCuulrkie. tUemnlpikeer abtuurlek, TCCo2=Ge8,1 t5hKe aasn-md aadpep rCeoci2aGbelenaconeorpcaivrtiitcyl,eHs cw=er7e0 smupTe.rTphaerasemeanghnaenticceadt proroopmertetimespmeriagthutreb eduatet rtiobtuhteeidr tsomaalnl epwalrytifcolermsiezde.o rHthoowrehvoemr,b tichep haansneewalietdh anaconmoppaorstiictiloesn wricehree rfienrrCoomaangdnewtiicthwsiltihg hat lyhiignhcreCausreide cte/amrpaetiroa.tuFruer,t ThCer= h8e1a5t iKn ganleda dapsptoreacniaibnlcerceoaeserciinviTtyC, tHoc8=7 070K m. TTh. eThmeasge neenthicaannceddsptrruocptuerrtailesp rmoipgehrtt ibees watetrriebucotends itsote antnwewitlhy efolermmeendt aolrtmhoaprhpoinmgboicbpsehravsaet iwonitsh. aT hcoemasp-omsiatdioenp raicrthieclre isnsChoow antdh awt iCtho salnigdhGtlye aintocrmeasswederec/laocraatteiod. sFeupratrhaetrelhyeoavtienrgt hleeapdasr ttioclaens. iHncorweaesvee ri,nt hTeCntoa n8o7p0aKrt.i cTlehse amnnaeganleetdicaat n82d3 sKtrushctouwraal upnroifpoerrmtiedsi swtreibreu tcioonnsoifstCeonta nwditGheealetommesntsaulg mgeasptipnignga soinbsgelervpahtaiosne.s.T Thheef uarst-hmeraadnenpeaarletidclneasn sohpoawrtitchleast sChoo awndCoG-seeagtroemgast wioenraetlothceatpeadr tsiecplearsautreflayceovaenrdththei spacortuicldlese.xHploawinetvheer,s tmhaelnl ainncorpeaasreticinleTsCantone8a7l0edK a. t 823 K show a uniform distribution of Co and Ge atoms suggesting a single phase. The further annealed nanoparticles show Co-segregation at the particle surface and this could explain the small the data, and drafted the manuscript. F.M.A performed the TEM measurements and interpreted the data. B.B. performedincrease in theTCSTEMto 870 K. measurements, interpreted the data and edited the manuscript, R.S., D.J.S. interpreted the data and edited the manuscript. G.C.H. interpreted the data, edited the manuscript and supervised the work. Author Contributions: O.T. performed the experiments, characterized the samples, analyzed and interpreted the data, and drafted the manuscript. F.M.A performed the TEM measurements and interpreted the data. B.B. Funding: This research is supported by Department of Energy (DOE) with grant number DE-FG02-04ER46152 performed the STEM measurements, interpreted the data and edited the manuscript, R.S., D.J.S. interpreted the and DE-FG02-90ER45413. data and edited the manuscript. G.C.H. interpreted the data, edited the manuscript and supervised the work. All authors contributed to the scientific discussion and approved the final version of the manuscript. Conflicts of Interest: The authors declare no conflict of interest. Funding: This research is supported by Department of Energy (DOE) with grant number DE-FG02-04ER46152 and DE-FG02-90ER45413. References Acknowledgments: The authors thank to Alexander Gabay for his useful suggestions. 1. Gambardella, P.; Rusponi, S.; Veronese, M.; Dhesi, S.S.; Grazioli, C.; Dallmeyer, A.; Cabria, I.; Zeller, R.; Conflicts of Interest: The authors declare no conflict of interest. Publisher Copyright: {\textcopyright} 2019 by the authors. Licensee MDPI, Basel, Switzerland.",
year = "2019",
month = oct,
doi = "10.3390/nano9101371",
language = "English (US)",
volume = "9",
journal = "Nanomaterials",
issn = "2079-4991",
publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",
number = "10",
}