From: Jim Choate <ravage@EINSTEIN.ssz.com>
Date: Wed, 31 Jul 1996 12:50:43 +0800
To: cypherpunks@toad.com
Subject: update.281 (fwd)
Message-ID: <199607310230.VAA04062@einstein>
MIME-Version: 1.0
Content-Type: text



Hi all,

Forwarded message:

> Date: Mon, 29 Jul 96 10:18:54 EDT
> From: physnews@aip.org (AIP listserver)
> Subject: update.281
> 
> PHYSICS NEWS UPDATE                         
> The American Institute of Physics Bulletin of Physics News
> Number 281  July 29, 1996  by Phillip F. Schewe and Ben Stein
> 
> SOLAR NEUTRINO FLUX IS NOT CORRELATED WITH
> SUNSPOT ACTIVITY.  The Kamiokande detector, situated a
> 
> THE PHYSICS OLYMPIAD IN OSLO, like the sports Olympiad
> 
> TUNNEL JUNCTION MAGNETORESISTANCE may lead to
> higher-density magnetic storage devices.  Physicists have known for
> some time that sandwiches of alternating magnetic and nonmagnetic
> microlayers can undergo a change in electrical resistance in the
> presence of an external magnetic field (arising, say, from a tiny
> domain on a segment of magnetic tape).  This magnetoresistance
> (MR) effect  can be used to decode binary data and has been
> employed in reading heads in computer hard drives.  Giant
> magnetoresistance (GMR), a stronger version of MR, affords even
> greater data-decoding sensitivity.  Prototype hard-drives with read
> heads using GMR have achieved areal data densities of 3
> Gbits/sq.in. Tunnel junction magnetoresistance (JMR) is yet another
> approach to transforming a tiny magnetic field into a change in
> resistance.  Unlike the all-metal GMR sensor, a room-temperature
> JMR sensor consists of two metal (ferromagnetic) layers  separated
> by an insulating layer.  A JMR trilayer junction tested recently at
> MIT is only 20 nm thick  and the signal (the fractional change in
> resistance) was 23%, compared to a signal of less than 7%  for a
> 40-nm-thick, 4-layer GMR prototype.  MIT physicist Jagadeesh
> Moodera (moodera@slipknot.mit.edu; 617-253-5423) suggests that
> the more compact size, relatively larger signal, and the low sub-nanoamp operating current of the JMR sensor could make for easier
> engineering of devices and lower production costs.  An areal density
> of more than 10 Gbits/sq.in. is possible, he says.  (J.S. Moodera et
> al., Applied Physics Letters, 29 July.)
>