New research may solve key problem in physics

Binghamton University physicist Michael Lawler and his colleagues have made a breakthrough that could lead to advances in superconductors. Their findings were published this week in the British journal Nature.

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Superconductors are materials – often but not always metals – that conduct electricity without resistance below a certain temperature. For decades, it was thought that these materials could conduct electricity only at temperatures far below freezing. In the last 20 years, however, scientists have discovered several compounds that superconduct at much higher temperatures.
In principle, a room-temperature superconductor could allow:

Electricity to travel with zero energy loss from power plants to houses.

High-speed trains to float on top of the superconductor.

Cell phone towers that could handle many cell phone carriers in high-population areas.

“It’s one of the most interesting problems that we have in physics,” Lawler said. “I believe that having a challenge at that level can help produce breakthroughs in science.”

Collected from: New research may solve key problem in physics » Binghamton University Research News - Insights and Innovations From Binghamton University

How Superconducting Levitation Works

Collected from: YouTube - How Superconducting Levitation Works

Pseudogap

A pseudogap is a term from the field of high-temperature superconductivity which describes an energy (normally near the Fermi energy) which has very few states associated with it. This is very similar to a 'gap', which is an energy that has no allowed states. Such gaps open up, for example, when electrons interact with the lattice. The Pseudogap is a zone of the Phase diagram generic.

A pseudogap is only observed in hole-doped Cuprate superconductors. And isotope effect is only emerged on the boundary of phases between superconducting and pseudogap state.

Collected from: Pseudogap - Wikipedia, the free encyclopedia

Key Advance in Understanding ‘Pseudogap’ Phase in High-T_c Superconductors

May lead to ways to overcome barrier to room-temperature superconductivity in copper-oxides

This pattern shows the tunneling potential of electrons on oxygen atoms “north” and “east” of each copper atom (shown embedded in the pattern) in the copper-oxide layer of a superconductor in the pseudogap phase. On oxygen atoms north of each copper, the tunneling potential is strong, as indicated by the brightness of the yellow patches forming lines in the north-south direction. On oxygen atoms east of each copper, the tunneling potential is weaker, indicated by less intense yellow lines in the east-west direction. This apparent broken symmetry may help scientists understand the pseudogap phase of copper-oxide superconductors.

Scientists have been trying for some 20 years to understand why the low temperature at which copper-oxide superconductors carry current with no resistance can’t be increased to be closer to room temperature. Recently, scientists have focused on trying to understand and control an electronic phase called the “pseudogap” phase, which is non-superconducting and is observed at a temperature above the superconducting phase. But what form of electronic order (if any) characterizes the pseudogap phase has remained a frustrating and challenging mystery.

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Across the entire copper-oxide crystal, the scientists found a remarkable difference in the electronic states associated with the mysterious pseudogap phase: The number of electrons able to “tunnel” to the microscope tip differed depending on the position of the oxygen atom relative to the copper atom. “Picture the copper atom at the center of the unit, with one oxygen to the ‘north’ and one to the ‘east,’ and this whole unit repeating itself over and over across the copper-oxide layer,” Davis said. “In every single copper-oxide unit, the tunneling ability of electrons from the northern oxygen atom was different from that of the eastern oxygen.”

The discovery of this asymmetrical behavior could be a breakthrough in understanding and controlling high-temperature superconductors because, historically, uncovering the reductions in symmetry responsible for other states of matter has led to huge advances in understanding and achieving control over those states. For example, discovery of the symmetries broken in liquid crystals eventually led to their control and everyday use in liquid crystal displays (LCDs).