University of Pennsylvania

Rodolfo Antonio Alvarez

Sergei V Kalinin

Dawn A Bonnell

A method for determining a magnetic force profile of a sample by using a cantilevered probe having a magnetic tip, the method comprising the steps of: traversing the tip along a predetermined path on the surface of the sample, the tip being proximate the surface of the sample while traversing along the predetermined path; determining the sample surface topography along the path; substantially canceling the sample surface potential along the path using the determined sample surface topography; and determining magnetic force data along the path based on the determined surface topography, wherein the determined magnetic force data is not magnetic force gradient data and the determined magnetic force data includes substantially no components from the sample surface potential.

Spatially resolved electromagnetic property measurement

A ferroelectric substrate () is patterned using local electric fields from an apparatus () to produce nanometer sized domains with controlled surface charge (), that allow site selective metalization () and subsequent reaction with functional molecules (), resulting in nanometer-scale molecular devices.

Directed assembly of nanometer-scale molecular devices

A scanning probe detects phase changes of a cantilevered tip proximate to a sample, the oscillations of the cantilevered tip are induced by a lateral bias applied to the sample to quantify the local impedance of the interface normal to the surface of the sample. An ac voltage having a frequency is applied to the sample. The sample is placed at a fixed distance from the cantilevered tip and a phase angle of the cantilevered tip is measured. The position of the cantilevered tip is changed relative to the sample and another phase angle is measured. A phase shift of the deflection of the cantilevered tip is determined based on the phase angles. The impedance of the grain boundary, specifically interface capacitance and resistance, is calculated based on the phase shift and the frequency of the ac voltage. Magnetic properties are measured by applying a dc bias to the tip that cancels electrostatic forces, thereby providing direct measurement of magnetic forces.

Growing community of inventors

Philadelphia, PA, United States of America

Rodolfo Antonio Alvarez