Boehme group

Illustration of the experiment that allows for the pulsed inverse spin Hall effect detection reported in nature materials, April 18 2016.

Exploration of spin currents in organic semiconductors (OSECs) induced by resonant microwave absorption in ferromagnetic substrates is appealing for potential spintronics apications. Owing to the inherently weak apin-orbit coupling (SOC) of OSECs, their inverse spin Hall effect (ISHE) response is very subtle; limited by microwave power applicable under continuous-wave (cw) excitation. Here we introduce a novel approach for generating significant ISHE signals in OSECs using pulsed ferromagnetic resonance, where the ISHE is two to three orders of magnitude larger compared to cw excitation.
This strong ISHE enables us to investigate a variety of OSECs ranging from π-conjucated polymers with strong SOC that contain intrachain platinum atoms, to weak SOC polymers, to C60 films, where the SOC is predominantly caused by the curvature of the molecule's surface. The pulsed-ISHE technique offers a robust route for efficient injection and detection schemes of spin currents at room temprature.

Illustration of the experiment that demonstrates the control of electric current by nuclear spins reported in Science 345, 1487 (2014).

In organic semiconductor materials hydrogen atoms are abundant, and since their nuclear spins (protons) have a strong influence on the charge carrier spins through the so-called hyperfine coupling, electric current and overall optoelectronic materials properties depend on hydrogen nuclear spins.
This study corroborated this mechanism by direct observation of the “fingerprint” of nuclear spin motion on the electric current in OLEDs under standard room temperature device operation conditions. By measuring charges emitted by OLED devices after a brief magnetic resonant excitation of charge carrier spins, the influence of nuclear-spin motion onto the charge-carrier spins and thus, the electric current was detected.

Illustration of our electric readout scheme reported in Nature Commun., 3, 898 (2012).Magnetometers based on organic magnetoresistance are limited by narrow sensitivity ranges, degradation and temperature fluctuations. Baker et al. demonstrate a magnetic resonance-based organic thin film magnetometer, which overcomes these drawbacks by exploiting the metrological nature of magnetic resonance.

Illustration of our electric readout scheme reported in Science, 330, 1652 (2010). The electron spins of free electrons are illustrated by green arrows, the donor electrons by blue arrows, the nuclear spins by red arrows. The surface illustrates the potential surface of the conduction band, the cones are the potential distortion in the vicinity of the phosphorous atoms. The nuclear spin is read by reading the donor electron spins at the phosphorous atoms which are hyperfine coupled to the nuclear spin. When the nuclear spin is down (left cone), the electron spin is up and thus, it can trap one of the free electrons which are all polarized in a spin-down orientation. This trapping reduces the free electron mobility and thus, the electric current. When the nuclear spin is up (right cone), the electron spin is down and thus, it can not trap one of the free electrons. The free electron mobility is therefore higher and the current is higher, too.

Inverse spin Hall effect: A new way to get electricity from magnetism
Read more at: http://unews.utah.edu/a-new-way-to-get-electricity-from-magnetism/

Nuclear spins control current in plastic LED: Step toward quantum computing, spintronic memory, better displays Read more at: http://phys.org/news/2014-09-nuclear-current-plastic-quantum-spintronic.html#jCp