Featured Research

from universities, journals, and other organizations

Microscale System To Study Frustration In Buckled Monolayers Of Microspheres

Date:
December 29, 2008
Source:
University of Pennsylvania
Summary:
Physicists have demonstrated a simple system based on micron-sized spheres in water to study and control geometric frustration. Their research elucidates open questions about frustration and frustration relief and provides a new tool for scientists grappling with these issues in a variety of fields from magnetism to basic statistical mechanics.

A team of University of Pennsylvania physicists has demonstrated a simple system based on micron-sized spheres in water to study and control geometric frustration. Their research, published today in the journal Nature, elucidates open questions about frustration and frustration relief and provides a new tool for scientists grappling with these issues in a variety of fields from magnetism to basic statistical mechanics.

Frustration is a feeling known to anyone who has had to choose one course of action from a range of imperfect options. Similar situations arise in nature, and scientific ideas about frustration have been explored to understand materials as varied as water, ceramics, magnets and superconductors.

"Our experimental situation is somewhat akin to the situation faced by a party host aiming to arrange dinner seating so that men are fully surrounded by women and women are fully surrounded by men," Arjun Yodh, professor in the Department of Physics and Astronomy at Penn, said. "If the host chooses tables with odd numbers of seats, then the seating goal cannot be achieved, and some people will be frustrated. If the host chooses square tables, then all of the men can have two female neighbors and all of the women can have two male neighbors, and everyone is happy.

"We created a similar sort of packing frustration by arranging spherical particles in water on a flat triangular lattice, while permitting the particles to freely move small distances out of plane, that is, up or down," Yodh said. "The frustrated material is formed because neighboring particles prefer to move away from one another. Thus, if a particle is in the down position, its neighbors will want to move to the up position. In our case, the microspheres pack on the corners of each triangle, and the lattice is said to be geometrically frustrated. For every triangle, there is always at least one pair of energetically unfavorable neighbors that are both up or both down."

This multiplicity of imperfect choices leads to frustrated materials with many "lowest energy" states in which small perturbations can introduce giant fluctuations with peculiar dynamics. Traditionally, these phenomena have been explored in magnetism, wherein spins on each atom experience frustration as a result of their anti-ferromagnetic near-neighbor interactions and the lattice on which they sit. But it is difficult to observe individual spins directly.

"We use microscopy to directly visualize the configurations and dynamics of all the 'spins' in the sample," said Yilong Han, a member of the Penn team and currently an assistant professor of physics at Hong Kong University of Science and Technology. "This is a major advance over previous experimental work, and, furthermore, we can use small changes in temperature to change the strength of the inter-particle interactions."

The ability to control inter-particle interactions enabled the Penn scientists to control the degree of frustration in the sample and concurrently probe material responses. The team found that the lattice deforms to relieve frustration as the material becomes more strongly frustrated.

"At high compaction or interaction strength, the in-plane lattice deformed into stripes and zigzags so that the microspheres were able to pack more efficiently," Tom Lubensky, professor and chair of the physics and astronomy department at Penn, said. "We were able to understand theoretically why these particular configurations relieved system frustration using a simple geometrical model tiling the plane with isosceles triangles."

"The slow sample dynamics also offer insights into the interplay between frustration relaxation and order," Yair Shokef, a post-doctoral Fellow and theorist with the team, said. "Deep connections between frustrated materials and glasses might exist, and we are now in a position to explore these possible connections."

Since the experimental scenario emulates classic models of spin frustration, the research builds a novel connection between two very different fields of physics: soft matter and frustrated magnetism. In the near future, novel energy landscapes can be created for the microspheres using laser tweezers and enabling experimenters to directly probe the role of lattice deformability on the dynamics and creation of structure. Similarly, optical and magnetic traps can be used to "flip" and move individual particles, experiments impossible with traditional magnetic materials.

The study, funded by the National Science Foundation, was conducted by A. M. Alsayed, P. Yunker, Lubensky and Yodh from the Department of Physics and Astronomy at Penn; Shokef, formerly of Penn and now with the Weizmann Institute of Science in Israel; and Han, formerly with Penn from Penn and now currently with the Hong Kong University of Science and Technology.


Story Source:

The above story is based on materials provided by University of Pennsylvania. Note: Materials may be edited for content and length.


Cite This Page:

University of Pennsylvania. "Microscale System To Study Frustration In Buckled Monolayers Of Microspheres." ScienceDaily. ScienceDaily, 29 December 2008. <www.sciencedaily.com/releases/2008/12/081217190340.htm>.
University of Pennsylvania. (2008, December 29). Microscale System To Study Frustration In Buckled Monolayers Of Microspheres. ScienceDaily. Retrieved September 3, 2014 from www.sciencedaily.com/releases/2008/12/081217190340.htm
University of Pennsylvania. "Microscale System To Study Frustration In Buckled Monolayers Of Microspheres." ScienceDaily. www.sciencedaily.com/releases/2008/12/081217190340.htm (accessed September 3, 2014).

Share This



More Matter & Energy News

Wednesday, September 3, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Halliburton Reaches $1B Gulf Spill Settlement

Halliburton Reaches $1B Gulf Spill Settlement

AP (Sep. 2, 2014) Halliburton's agreement to pay more than $1 billion to settle numerous claims involving the 2010 BP oil spill could be a way to diminish years of costly litigation. A federal judge still has to approve the settlement. (Sept. 2) Video provided by AP
Powered by NewsLook.com
Google Teases India Event, Possible Android One Reveal

Google Teases India Event, Possible Android One Reveal

Newsy (Sep. 1, 2014) Google has announced a Sept. 15 event in India during which they're expected to reveal their Android One phones. Video provided by Newsy
Powered by NewsLook.com
Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins