S. Nicoletti

Publications (1)1.36 Total impact

• Article: Temperature Dependence of Magnetotransport in Extraordinary Magnetoresistance Devices

  T.D. Boone, L. Folks, J.A. Katine, S. Maat, E. Marinero, S. Nicoletti, M. Field, G.J. Sullivan, A. Ikhlassi, B. Brar, B.A. Gurney
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  ABSTRACT: Extraordinary magnetoresistance (EMR) devices have been fabricated and characterized at various magnetic fields, operating temperatures, and current excitations. These devices are comprised of nonmagnetic high mobility semiconductors and low resistance metallic contacts and shunts. The resistance of the device is modulated by magnetic fields due to the Lorentz force steering an electron current between the high resistance semiconductor and the low resistance metallic shunt. The EMR devices were tested between 300 K and 5 K in magnetic fields up to 2 T perpendicular to the 2DEG plane and excitation currents up to 100 muA. Magnetoresistance increases as temperature decreases, potentially indicating that EMR persists even as dimensions approach the electron mean free path
  IEEE Transactions on Magnetics 11/2006; · 1.36 Impact Factor
• Article: Finite element modeling of the bit-resolution of EMR sensors with I+/V+/I-/V-lead geometry

  S. Moat, A. Chattopadhyay, T. D. Boone, L. Folks, E. Marinero, J. A. Katine, S. Nicoletti, B. A. Gurney
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  ABSTRACT: Summary form only given. Extraordinary magneto-resistance (EMR) read sensors are promising candidates for high density magnetic recording as they do not contain any magnetic material. Thus, they do not suffer from magnetic noise due to thermal fluctuations at small dimensions as observed in conventional giant magnetoresistive (GMR) or tunnel-valve sensors or spin-torque noise at high current densities as observed in current perpendicular to the plane GMR sensors. We used the finite element method (FEM) to model the response of EMR sensors comprising an AlSb/InAs (12 nm)/AlSb electron quantum well structure with a sheet resistance of 300 Omega/sq and a room temperature mobility of mu = 1.6/Tesla. The EMR sensors with I+/V+/ I-/ V-lead geometry were processed by using conventional e-beam techniques. Gold was used for the leads and shunt with a contact resistance to the quantum well of about 3 times10-6 Omegacm2. The spacing between the edges of the voltage and I-leads is 100 nm. The model shows that higher signals can be achieved when the lead geometry is (I+/V+/I-/V-) as compared to the geometry originally described by Solin, et al. (I+/V+/V-/I-). Moreover, our calculations show that in this geometry an EMR sensor, although its dimension may be larger than the magnetic bit to be sensed itself, still can act as a local sensor. We further show that the response is solely determined by the spacing and positioning of the voltage leads with respect to the bit. Our FEM calculations are in good agreement with experimental data. We measured a resistance change of DeltaR~390 mOmega/Oe when exciting the whole sensor. The FEM model fits the data assuming a mobility of mu = 1 / Tesla.
  01/2006;