By developing a way to better measure and manipulate conductive materials through scanning tunneling microscopy, Researchers from Japan have taken a step toward faster and more advanced electronics. In Scanning Tunneling Microscopy (STM), a conducting tip close to the surface of the conductive material to be imaged is placed. By creating a “tunnel junction” between the two through which electrons travel, a voltage is applied through the tip to the surface.
To provide the scientist with a better understanding of the atomic structure of the material being imaged the shape and position of the tip, the voltage strength, the conductivity and density of the material’s surface all come together. The scientist should be able to change the variables to manipulate the material itself with that information. Till now the precise manipulation is a problem. Within the desired electrical current, the custom terahertz pulse cycle designed by the researchers quickly oscillates between near and far fields.
A scientist said “The active control and characterization of near fields in a tunnel junction are essential for advancing elaborate manipulation of light-field-driven processes at the nanoscale.” Via terahertz scanning tunneling microscopy with a phase shifter, we demonstrated that desirable phase-controlled near fields can be produced in a tunnel junction.”
Previous studies assumed that spatially and temporally the near and far fields were the same. Along with examining the fields closely the Team identified that there was a difference between the two and realized that to switch the current to the near field, the fast laser pulse could prompt the needed phase shift of the terahertz pulse.
For optical storage media in DVDs and Blu-ray as well as next-generation ultrafast electronics and microscopies the phase change materials used. So the scientists said their work holds enormous promise for advancing strong-field physics in nano-scale solid state systems.