Starting at 135 degrees below zero Fahrenheit, a temperature nearing the record low in Antarctica, researchers at UCLA discovered an unexpected way to extend quantum properties to temperatures well above room temperature. The team found that adding the amino acid arginine to tantalum disulfide enabled the material to exhibit a commensurate charge density wave (CCDW) at temperatures as high as 135 degrees Fahrenheit.
This structural arrangement, with two layers of arginine sandwiched between single layers of tantalum disulfide, contrasts sharply with other amino acids tested, which showed no such effect. The findings may open design possibilities for advanced materials, potentially leading to energy-efficient computer memory based on quantum properties.
CCDW Behavior Extended Above Room Temperature via Amino Acid Addition
The addition of arginine enabled the observation of commensurate charge density wave (CCDW) behavior in tantalum disulfide at temperatures reaching 135 degrees Fahrenheit, a significant expansion from the initial observation point of 135 degrees below zero. This achievement represents a substantial increase in the operational temperature range for this quantum phenomenon, bringing it closer to practical applications. Prior to this work, the CCDW state in tantalum disulfide was limited to extremely low temperatures, comparable to those found in the coldest regions of Antarctica.
This precise layering proved critical, as experiments with two other amino acids yielded no similar results at room temperature. The team’s initial screening of over 50 carbon-based molecules revealed arginine as a unique candidate, a finding that emerged during later analysis of the combined material. Computer simulations subsequently confirmed how arginine’s molecular structure and electron distribution contribute to the observed quantum effects.
The CCDW itself represents a departure from typical metallic behavior, where electrons move randomly and are easily disrupted by thermal vibrations. Instead, the CCDW forces electrons to move in a coordinated pattern, aligning with distortions in the material’s crystal structure. “Normally, electrons move more or less randomly through a metal and are easily bumped off course by small-scale vibrations caused by ambient heat,” the researchers explain, highlighting the contrast between conventional electron behavior and the orderly motion enabled by the CCDW.
This orderly flow could be harnessed for future technologies, but the need for cryogenic cooling previously presented a major obstacle. The investigators’ approach of using molecular chemistry to modify the electronic properties of inorganic crystals is noteworthy.
Xiangfeng Duan, the study’s corresponding author and holder of UCLA’s Raymond A. and Dorothy A. Wilson Endowed Chair, and his team demonstrate a rare instance of inorganic materials chemists using organic molecules to tune the behavior of inorganic materials. This methodology could broaden the design possibilities for advanced materials, potentially incorporating other biomolecules to achieve desired properties. The research team used a variety of techniques, including measurements of vibrations, electrical flow, temperature changes and atomic structure, to characterize the modified material.
These analyses, combined with theoretical work led by Zhenglu Li, a professor of engineering at USC, established a clear link between the arginine molecule and the altered quantum behavior. Co-authors from Tamkang University in Taiwan, UC Irvine and the University of Chemistry and Technology, Prague, further contributed to the comprehensive investigation. The potential implications of this work extend to the development of energy-efficient computer memory.
The team envisions a new type of storage based on quantum properties, rather than the electrons used in traditional electronics. They state that this success with arginine could inform a new approach, where researchers start with a desired material property, such as superconductivity, and then identify or create molecules to achieve it.
“The specifications that made arginine such a perfect match for tantalum disulfide could one day inform rational design,” the researchers suggest, hinting at a future where molecular engineering unlocks new material capabilities. The findings of this study have been published in Nature Chemistry, supported by funding from the U.S. National Science Foundation, the U.S. The team’s next steps will focus on deepening their understanding of both the material itself and the underlying mechanisms driving its behavior.
Source: https://newsroom.ucla.edu/releases/amino-acid-extends-quantum-properties-above-room-temperature
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