The fluctuations associated with quantum-critical points, i.e., second-order phase transitions at zero temperature, have been considered crucial for the stabilization of intriguing phenomena, such as superconductivity or non-Fermi liquid behavior. This motivates the search for novel states by tuning magnetic phase transitions towards 0 K by external parameters, such as physical pressure or chemical substitutions. For clean metallic ferromagnets, it is widely believed that quantum criticality is avoided for generic reasons. It was proposed that the metallic ferromagnet LaCrGe3 is… more

Two recent articles from a team of researchers at Penn State University highlighted the compression of aromatic compounds to make new derivatives of diamond nanothread architectures. Nanothreads are rigid, one-dimensional ordered polymers theorized to possess extraordinary tensile strength, extreme stability over a small diameter, and unique electronic properties inaccessible by sp2-rich carbon material analogues. However, the high pressure for synthesis (often exceeding 23 GPa) prevents wide-scale commercial use. Thus, efforts to reduce the pressure… more

Polymers are becoming increasingly important in defense, medical and aerospace applications, as they have many desirable properties that can be tailored by varying their chemistry. One such polymer, polyurea, is an amorphous block-copolymer with “hard” and “soft” molecular segments that has shown exceptional performance as a coating for blast mitigation, impact resistance, and shock wave attenuation.

A thorough understanding of the atomic and molecular level response of polymers used in defensive coatings under high pressures is key in designing these coatings and formulating… more

One of the unanswered questions in physics is the time dependence of phase diagrams and how to model it. When a material is loaded dynamically through equilibrium phase boundaries, it is the kinetics that determines the real time expression of a phase transition. That in turn can play a significant role in the thermodynamic path that the material takes and its end state.

However, the role that kinetics of phase transitions play in a material’s constitutive properties is not well understood. This lack of understanding is due to a lack of experimental data of… more

Finding new exotic magnetic states arising from geometric frustration is a central focus in condensed matter physics today. One such state, marked by the absence of long-range magnetic ordering in the presence of strong magnetic coupling—even at absolute zero temperature—is the quantum spin liquid. High applied pressures offer several avenues to tune magnetic properties towards new exotic magnetic states. As increasing pressure modifies bond lengths, magnetic coupling interactions can be tuned towards a quantum critical point.  Additionally, high pressure can stabilize metastable… more

The ability to understand and predict the response of matter at extreme conditions requires knowledge of a material’s equation-of-state, including the location of phase boundaries, transition kinetics, and the evolution of material strength.  Cerium is a material with a complex phase diagram that continues to attract significant scientific interest.  A recent publication, Dynamic experiments to study the α−ϵ phase transition in cerium (B. J. Jensen and F. J. Cherne from LANL and N. Velisavljevic, HPCAT/LLNL) J. Appl. Phys. 127, 095901… more

A recent article in Science Advances has been selected as one of the Advanced Photon Source's science highlights.  The team of researchers, led by Tim Strobel and Li Zhu of Carnegie Institution for Science, used advanced structure searching tools to predict the first thermodynamically stable carbon-based clathrate and then synthesized the clathrate… more

HPCAT Group Leader, Maddury Somayazulu, was recently featured in the October 2019 issue of Scientific American.  The article highlights some of Dr. Somayazulu’s scientific work, and in particular his effort in using high pressure and synchrotron x-ray techniques toward understanding and discovery of room-temperature superconductors.  Dr. Somayazulu, along with HPCAT partner Professor Rus Hemley (University of Illinois at Chicago) and collaborators from Geophysical… more