INFM – National Research Center – Modena - Italy Alessandro di Bona (MO) Marco Liberati (MO) Paola Luches* (MO) Sergio Valeri (MO) Gian Carlo Gazzadi (MO) Paolo Vavassori (FE) Diego Bisero (FE) * researcher position supported by this FIRB project FIRB: Microsistemi basati su materiali magnetici innovativi strutturati su scala nanoscopica Nanopatterned Fe films

INFM – National Research Center – Modena - Italy the Fe/MgO system epitaxial growth lattice mismatch < 3.5% easy substrate preparation (cleavage in air) no interaction with the substrate < 0.02 e - /atom O Mg Fe Febcc MgOrocksalt (two fcc) interface distance 2.30 Å MgOsubstrate (100) 10 nm Fe 10 nm MgO FIB free standing nanostructures

INFM – National Research Center – Modena - Italy the Fe/MgO continuous film XPSXPD SEIMgO(001) Fe/MgO(001) LEEDMgO(001) Fe/MgO(001)

INFM – National Research Center – Modena - Italy Geometry of Dual Beam FEI Strata DB 235 Beams work at coincidence on the sample: FIB machining + simultaneous SEM imaging on a nanometer scale. 3 nm, 1 – 30 keV 7 30 keV Coincidence 1 pA – 50 nA 1 pA – 20 nA Current range 200 eV – 30 keV 5 – 30 keV Energy range SFEG Ga + LMIS Source type SEMFIB High Vacuum: 5x mbar FIB + SEM = dual beam FIB SEM

INFM – National Research Center – Modena - Italy inside the FIB suppressor & LMIS extractor cap lens 1 beam defining aperture beam blanking deflection octopole lens 2 the FIB column LMIS is a field–emission point- source. High brightness: hundreds of pA in sub- m beam ion-solid interactions are effective. Liquid wets a W needle. At the needle tip liquid faces HV and forms the Taylor cone: field ion emission starts. Gallium because of high surface tension and low vapor pressure at a low melting point. Durable sources the Liquid Metal Ion Source (LMIS)

INFM – National Research Center – Modena - Italy FIB machining & FIB deposition precursor gas injector deposited metal

INFM – National Research Center – Modena - Italy dual beam applications 200 nm 100 nm 50 nm

INFM – National Research Center – Modena - Italy MgO/Fe/MgO micropatterning 500 μm 10 μm

INFM – National Research Center – Modena - Italy micropattern characterization SEM AFM

INFM – National Research Center – Modena - Italy magnetic characterization MOKE micromagnetometer lateral resolution < 30 μm

INFM – National Research Center – Modena - Italy magnetic characterization continuous film K = 4-5 · 10 5 erg/cm 3 Fe(100) easy Fe(110) hard...and no perpendicular magnetization component

INFM – National Research Center – Modena - Italy magnetic characterization circular dots Fe(100) easy Fe(110) hard coercitive field larger with respect to film = μ-magnetic OK

INFM – National Research Center – Modena - Italy magnetic characterization squared dots with side // to the hard axis Fe(100) easy Fe(110) hard different shape anisotropy causes even larger cohercitive field

INFM – National Research Center – Modena - Italy magnetic characterization squared dots with side // to the easy axis Fe(100) easy Fe(110) hard different configuration anisotropy for different orientations

INFM – National Research Center – Modena - Italy conclusions Fe microstructures successifully fabricated by FIB the MgO passivation works the Fe film crystal quality is OK the geometric quality of the microstructures is good the geometry of the microstructures changes their magnetic response to do... to improve the geometric quality of the structures (FIB) to reduce the size of the structures micromagnetic simulations of the magnetic behaviour

INFM – National Research Center – Modena - Italy