Visit the CCMR online at http://www.ccmr.cornell.eduResearch supported in part by NSF DMR-1120296

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New property of electrons may lead to novel
electronic devices How electrons conduct
electricity depends on their valley
To meet demand for smaller, more powerful
electronics, engineers are struggling to find
ways to store more information in a smaller area.
Todays computers store information digitally as
a series of 1s and 0s using two fundamental
properties of electrons their charge (which
enables flash drives) and their spin (which
enables hard disks). To date, advances in digital
storage have relied on a simple approach writing
smaller 1s and 0s. A recent breakthrough at
Cornell University may enable a different
approach. The Cornell team has shown that
electrons in single-molecule-thick films of
molybdenum disulfide (MoS2), a common lubricant,
have a third fundamental property a valley.
Half of the electrons in MoS2 are in one valley,
while the rest are in a second valley. An
electrons valley plays an important role in
determining how it conducts electricity,
potentially leading to a new way to store
information. This property also leads to the
newly observed valley Hall effect. The regular
Hall effect, first observed in 1879, is used in a
wide variety of sensors, including fuel gauges
and antilock brakes. The new valley Hall effect
may enable a new generation of electronic and
optoelectronic devices.

In the valley Hall effect, the motion of an
electrons is determined its valley, represented
here by color.
K. F. Mak, K. L. McGill, J. Park, P. L. McEuen,
Science 344, 1489 (2014).