A new topological insulator breaks symmetry, and that's a good thing

A new topological insulator breaks symmetry, and that's a good thing: Most topological insulators operate as either a p-type or n-type material on both top and bottom surfaces. But BiTeCl is asymmetric: p-type on its top surface and n-type on its bottom. This means the edges of the material could function as p-n junctions – or even many microscopic p-n junctions layered on top of each other. Even better, when the material is placed in a magnetic field, these p-n junctions develop unique edge channels that can conduct electricity with zero resistance, Chen said – and this opens all sorts of possibilities.

Moreover, this unique type of material can demonstrate many other phenomena. For instance, placing it in a static electric field can induce useful magnetic properties in the material, a phenomenon known as the topological magneto-electric effect, first predicted by theorist Shoucheng Zhang of the Stanford Institute for Materials and Energy Sciences and his group. You could even use an electric charge to induce magnetic monopoles – theorized magnets that have just one pole, north or south, rather than the usual two – and then use this exotic magnetic state to do practical work, such as storing information on a hard drive, Chen said. "This is very bizarre," he said, "because people have never found magnetic monopoles as fundamental particles."

Superconductor May Hide Long-sought Secret - Science News

Superconductor May Hide Long-sought Secret - Science News: To probe the material, Yoichi Ando of Osaka University and colleagues in Japan injected current into it using a gold wire. This excited electrons at the surface, creating ripples of energy. Conventional superconductors have a dead spot in their surfaces that prevents low-energy, slow-wobbling ripples from forming. But a close look at this material revealed a sea of waves bouncing up and down both quickly and slowly.

Ando says that this pattern of ripples is “unambiguous evidence” of a type of superconductivity never seen before: topological superconductivity, in which electrons become waves molded into a complex shape that resembles the outside of a doughnut. These waves, says Ando, seem to be behaving like exotic two-dimensional particles at the surface of the material — specifically, Majorana fermions.

“This is the best evidence so far for Majorana fermions in a solid material,” says Taylor Hughes, a theoretical physicist at the University of Illinois at Urbana-Champaign.

First observation of particles that are their own antiparticles could be on its way

First observation of particles that are their own antiparticles could be on its way: The device proposed by Onoda and his colleagues offers deliberate control over Majorana particles within a topological insulator that they hope will make them accessible to experiments. Their device consists of a surface of a superconducting topological insulator attached to two magnetic sections. The magnetic fields of the two magnets point in opposite directions. The researchers predict that, along the interface between the magnets, a periodic chain of magnetic field lines form in the superconducting topological insulator. Each of these magnetic field lines could accommodate a Majorana particle.
Once their existence is proved, Majorana particles could also enable extremely stable new forms of computing based on quantum physics, says Onoda.

Unique duality: 'Exotic' superconductor with metallic surface discovered

Unique duality: 'Exotic' superconductor with metallic surface discovered: The new material -- a crystal called a topological superconductor -- has two electronic identities at once. At very low temperatures, the interior of the crystal behaves like a normal superconductor, able to conduct electricity with zero resistance. At the same time, the surface is metallic, able to carry a current, albeit with some resistance.