Longitudinal and perpendicular exchange bias in FeMn/(FeNi/FeMn)n multilayers

Exchange bias in ferromagnetic (FM)/antiferromagnetic (AF) bilayers is usually investigated in the longitudinal configuration with the exchange coupling established in the film plane. In this work, we report on the perpendicular exchange bias in FeMn(8 nm)/[FeNi(2 nm)/FeMn(8 nm)]n multilayers induced by perpendicular field cooling. The thin FeNi layers give rise to large values of the exchange field and coercivity, and n=15 allows a sufficiently large magnetization for the measurements. Even though the soft FeNi layers have an intrinsic in-plane anisotropy, perpendicular exchange bias has been observed after cooling in a perpendicular external field. The exchange field in the perpendicular configuration is about 0.85 that of the longitudinal case. In both the longitudinal and perpendicular configurations, the exchange field decreases quasilinearly with temperature. The squareness of perpendicular hysteresis loops decreases with increasing temperature

Dynamic Observation of Electrochemical Etching in Silicon

The authors have designed and constructed a TEM specimen holder in order to observe the process of pore formation in silicon. The holder incorporates electrical feedthroughs and a sealed reservoir for the electrolyte and accepts lithographically patterned silicon specimens. The authors describe the system and present preliminary, ex situ observations of the etching process

Dynamic observation of electrochemical etching in silicon

The authors have designed and constructed a TEM specimen holder in order to observe the process of pore formation in silicon. The holder incorporates electrical feedthroughs and a sealed reservoir for the electrolyte and accepts lithographically patterned silicon specimens. The authors describe the system and present preliminary, ex situ observations of the etching process

Giant positive magnetoresistance of Bi nanowire arrays in high magnetic fields

We have studied the magnetoresistance of electrodeposited Bi wires with diameters between 200 nm and 2 μm in magnetic fields up to B=55 T. In zero field, the resistance increases with decreasing temperature, indicating that the mean free path is strongly influenced by the nanowire geometry. The high-field magnetoresistance shows strong dependence on field orientation; typically 200% for B parallel to the wires, and 600%-800% for B perpendicular to the wires. The perpendicular magnetoresistance is well described by a modified two-current model which suggests that the high-field response of the arrays is fairly insensitive to the wire diameter, and is dominated by bulk properties of Bi