(Press-News.org) Contact information: Lynn Yarris
lcyarris@lbl.gov
510-486-5375
DOE/Lawrence Berkeley National Laboratory
Crossover sound
Unambiguous evidence for coherent phonons in superlattices
We all learn in high school science about the dual nature of light - that it exists as both waves and quantum particles called photons. It is this duality of light that enables the coherent transport of photons in lasers. Sound at the atomic-scale has the same dual nature, existing as both waves and quasi-particles known as phonons. Does this duality allow for phonon-based lasers? Some theorists say yes, but the point has been argued for years. Recently a large collaboration, in which Berkeley Lab scientists played a prominent role, provided the first "unambiguous demonstration" of the coherent transport of phonons.
Ramamoorthy Ramesh, a senior scientist with Berkeley Lab's Materials Sciences Division, was a co-leader with Arun Majumdar, a former Associated Laboratory director at Berkeley Lab and
and currently VP for Energy at Google, of an experiment in which phonons underwent particle-to-wave crossovers in superlattices of perovskite oxides.
"Our observations open up new opportunities for studying the wave-like nature of phonons, particularly phonon interference effects," says Ramesh. "Such research should have potential applications in thermoelectrics and thermal management, and in the long run could help the development of phonon lasers."
Unlike elementary particles such as electrons and photons, whose wave nature and coherent properties are well-established, experimental demonstration of coherent wave-like properties of phonons has been limited. This is because phonons are not true particles, but the collective vibrations of atoms in a crystal lattice that can be quantized as if they were particles. However, understanding the coherent wave nature of phonons is of fundamental importance to thermoelectrics, materials that can convert heat into electricity, or electricity into heat, which represent a potentially huge source of clean, green energy.
"Lower thermal conductivity is one of the keys to improving the efficiency of thermoelectric materials and the key to thermal conductivity in semiconductors is phonon transport," Majumdar says. "Nanostructures such as superlattices are the ideal model systems for the study of phonon transport, particularly the wave-particle crossover, because the wavelength of the most relevant phonons are in the range of one to 10 nanometers."
Superlattices are artificial periodic structures consisting of two dissimilar semiconductors in alternating layers a few nanometers thick. For this demonstration, the collaboration synthesized high-quality superlattices of electrically insulating perovskite oxides on various single-crystal oxide substrates. Interface densities in these superlattices were
systematically varied using two different epitaxial growth techniques. Thermal conductivity was measured as a function of interface density.
"Our results were in general agreement with theoretical predictions of crossover from incoherent particle-like to coherent wave-like phonon transport," Ramesh says. "We also found sufficient evidence to eliminate extraneous or spurious effects, which could have alternatively explained the observed thermal conductivity minimum in these superlattices."
Capitalizing on the wave behavior of phonons should enable new advances in new heat transfer applications, the collaborators say. Furthermore, perovskite superlattice-based heterostructures could also serve as basic building blocks for the development of lasers in which beams of coherent phonons rather than coherent photons are emitted. Phonon lasers could provide advanced ultrasound imaging or highly accurate measuring devices, among other possibilities.
INFORMATION:
Ramesh is a corresponding author of a Nature Materials paper describing this research titled "Crossover from incoherent to coherent phonon scattering in epitaxial oxide superlattices." For a complete list of the co-authors go here
This research was primarily supported by U.S. Department of Energy's Office of Science.
Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www.lbl.gov.
Crossover sound
Unambiguous evidence for coherent phonons in superlattices
2014-02-06
ELSE PRESS RELEASES FROM THIS DATE:
Grasshoppers are what they eat
2014-02-06
PUBLIC RELEASE DATE: 5-Feb-2014
[
| E-mail
]
var addthis_pub="eurekalert"; var addthis_options = "favorites, delicious, digg, facebook, twitter, google, newsvine, reddit, slashdot, stumbleupon, buzz, more"
Share
Contact: Beth Parada
apps@botany.org
American Journal of Botany
Grasshoppers are what they eat
New method to extract plant DNA from grasshopper guts improves understanding of plant-insect interactions
VIDEO:
This is a demonstration of grasshopper ...
Heavy metal in the early cosmos
2014-02-06
Ab initio: "From the beginning."
It's a term used in science to describe ...
New study finds early universe 'warmed up' later than previously believed
2014-02-06
A new study from Tel Aviv University reveals that black holes, formed from the first stars in our ...
Whales and human-related activities overlap in African waters
2014-02-06
Scientists with the Wildlife Conservation Society, Oregon State University, Stanford ...
Obesity treatment using stem cells is the topic of 2013's most-visited news release on EurekAlert!
2014-02-06
For the second year in a row, obesity research features prominently in the group of 10 most-visited news releases posted on EurekAlert! ...
Fruit fly microRNA research at Rutgers-Camden offers clues to aging process
2014-02-06
CAMDEN — Diseases like Alzheimer's and Huntington's are often associated with aging, but the biological link between the two is less certain. Researchers at Rutgers University–Camden ...
New evidence shows increase in obesity may be slowing, but not by much
2014-02-06
CHAMPAIGN, Ill. — In his 2014 State of the Union address, President Barack Obama referred to an August 2013 Centers for Disease Control and Prevention study that showed a ...
Monkeys that eat omega-3 rich diet show more developed brain networks
2014-02-06
PORTLAND, Ore. — Monkeys that ate a diet rich in omega-3 fatty acids had brains with highly connected ...
MD Anderson guides intelligent redesign of cancer care delivery model
2014-02-06
HOUSTON – How best to implement key recommendations recently identified ...
Durable end to AIDS will require HIV vaccine development
2014-02-06
WHAT:
Broader global access to lifesaving antiretroviral therapies and wider ...
LAST 30 PRESS RELEASES:
Plant doctor: An AI system that watches over urban trees without touching a leaf
Study tracks chromium chemistry in irradiated molten salts
Scientists: the beautiful game is a silver bullet for global health
Being physically active, even just a couple of days a week, may be key to better health
High-fat diet promote breast cancer metastasis in animal models
A router for photons
Nurses and AI collaborate to save lives, reduce hospital stays
Multi-resistance in bacteria predicted by AI model
Tinker Tots: A citizen science project to explore ethical dilemmas in embryo selection
Sensing sickness
Cost to build multifamily housing in California more than twice as high as in Texas
Program takes aim at drinking, unsafe sex, and sexual assault on college campuses
Inability to pay for healthcare reaches record high in U.S.
Science ‘storytelling’ urgently needed amid climate and biodiversity crisis
KAIST Develops Retinal Therapy to Restore Lost Vision
Adipocyte-hepatocyte signaling mechanism uncovered in endoplasmic reticulum stress response
Mammals were adapting from life in the trees to living on the ground before dinosaur-killing asteroid
Low LDL cholesterol levels linked to reduced risk of dementia
Thickening of the eye’s retina associated with greater risk and severity of postoperative delirium in older patients
Almost one in ten people surveyed report having been harmed by the NHS in the last three years
Enhancing light control with complex frequency excitations
New research finds novel drug target for acute myeloid leukemia, bringing hope for cancer patients
New insight into factors associated with a common disease among dogs and humans
Illuminating single atoms for sustainable propylene production
New study finds Rocky Mountain snow contamination
Study examines lactation in critically ill patients
UVA Engineering Dean Jennifer West earns AIMBE’s 2025 Pierre Galletti Award
Doubling down on metasurfaces
New Cedars-Sinai study shows how specialized diet can improve gut disorders
Making moves and hitting the breaks: Owl journeys surprise researchers in western Montana
[Press-News.org] Crossover soundUnambiguous evidence for coherent phonons in superlattices