4 ms·
I know the HN protocol is to use the headline, but the sciencebulletin article headline is pretty broken. Negative differential resistance (NDR) in tunneling
by jpmattia 10y ago
I know the HN protocol is to use the headline, but the sciencebulletin article headline is pretty broken. Negative differential resistance (NDR) in tunneling diodes has been understood for several decades, and is pretty far from a mystery.
The original article is about an I-V curve from a structure involving a single-atom + a scanning-tunneling microscope (STM). That such a system would also exhibit NDR is not particularly surprising. Tunneling to a structure with discrete energy levels will have current flow when energies line up, and less current flow when energies don't line up. So even the "mystery" isn't much of a mystery.
The interesting results imho are:
1. The team got reproducible single-atom tunneling with an STM tip, and
2. They measured the time-response of about 10 microseconds.
fwiw.
Edit: Resonant tunneling diodes used to be a hobby of mine: https://dspace.mit.edu/handle/1721.1/38419 https://dspace.mit.edu/handle/1721.1/38419
- steamer25 10y agoFor anyone else who wondered, in this context STM stands for Scanning Tunneling Microscope (as opposed to Software Transactional Memory).
- justifier 10y agoit reads like there is a bit more 'mystery', or 'the yet explained', explained(o): > measuring current vs voltage in a new way, by applying brief voltage pulses to the STM tip. When the pulses lasted 10 microseconds or longer, they saw NDR. But when they reduced the pulse length to 10 nanoseconds, the effect disappeared. ... Combining this information with other data, the team determined the timescale for electrons refilling the empty lower level. unreal (o) https://physics.aps.org/articles/v9/155 https://physics.aps.org/articles/v9/155
- mtdewcmu 10y agoDo you agree that this is a major breakthrough, worth billions of dollars?