Shangqing Liu

6473332, Oct 29, 2002

Apr 4, 2001

09/826386

Alex Ignatiev - Houston TX
Naijuan Wu - Pearland TX
Shangqing Liu - Houston TX
E. Joseph Charlson - Houston TX

The University of Houston System - Houston TX

G11C 1100

365148, 36518503

An electrically operated, overwritable, multivalued, non-volatile resistive memory element is disclosed. The memory element includes a two terminal non-volatile memory device in which a memory film material is included, and a circuit topological configuration is defined. The memory device relates generally to a unique new electrically induced variable resistance effect, which has been discovered in thin films of colossal magnetoresistive (CMR) oxide materials. The memory material is characterized by: 1) the electrical control of resistance through the application of short duration low voltage electrical pulses at room temperature and with no applied magnetic field; 2) increase of the resistance or decrease of the resistance depending on the polarity of the applied pulses; 3) a large dynamic range of electrical resistance values; and 4) the ability to be set at one of a plurality of resistance values within said dynamic range in response to selected electrical input signals so as to provide said single cell with multibit/multivalued storage capabilities. The memory element includes a circuit topology to construct a ROM/RAM configuration. The features of the memory element circuit are: 1) the ability to set and then measure the resistance of the two terminal multi-valued memory devices with negligible effects of sampling voltage and current; and 2) the ability to step up or down the resistance value, i. e.

6762481, Jul 13, 2004

Oct 8, 2002

10/267010

Shangqing Liu - Houston TX
Naijuan Wu - Houston TX
Alex Ignatiev - Houston TX

The University of Houston System - Houston TX

H01L 2993

257595, 257312

A basic form of a variable capacitive apparatus and its actuating method are disclosed. The apparatus is a simple two-terminal structure and may be set by short duration, low voltage electrical pulses. Materials with perovskite structure or perovskite-related structures, especially colossal magnetoresistive materials, are the active constituents of the apparatus. The apparatus overcomes the shortcomings of its predecessors and offers the advantages of non-volatility, two or multi-level storage, non-destructive reading, free-of-power maintenance and potential high radiation hardness.

62041398, Mar 20, 2001

Aug 25, 1998

9/139994

Shangqing Liu - Houston TX
Naijuan Wu - Houston TX
Alex Ignatiev - Houston TX

University of Houston - Houston TX

H01L 2120

438385

A method for switching properties of perovskite thin film materials, including the colossal magnetoresitive (CMR) and high temperature superconducting (HTSC) materials, is provided. Short electrical pulses are applied to the materials in thin films to change both reversibly and non-reversibly the electrical, thermal, mechanical and magnetic properties of the material. Reversible resistance changes of over a factor of 10 are induced in CMR materials at room temperature and in zero external magnetic field by electrical pulsing. Applications of the method and materials to form memory devices, resistors in electronic circuits which can be varied in resistance and other applications are disclosed.