#SPIN ORBIT COUPLING SERIES#

As case studies, the blue-light emitting materials Pt(4,6-dFppy)(acac) and Ir(4,6-dFppy) 2(acac) are investigated and characterized in detail. The theoretical picture built up in this way can help engineers design novel devices and work out solutions to problems before entering into large-scale production.High-resolution optical spectroscopy of organometallic triplet emitters reveals detailed insights into the lowest triplet states and the corresponding electronic and vibronic transitions to the singlet ground state. The final ingredient is to include the response of the magnetization to the influence of changing currents. This information then feeds into models that describe the action of a current consisting of many electrons with different alignments. The first step is to use quantum physics to understand how a single electron interacts with a magnetized material.

#SPIN ORBIT COUPLING SERIES#

We break down the intricate phenomenon into a series of steps. The goal of our studies of spin-orbit torques is to advance theory to the point that it can reliably interpret measurements and enable rigorous and reliable predictions of how specific systems will perform in a range of possible device applications. This technique could make possible gigahertz oscillators with a wide range of electronic uses. In addition to memory devices like MRAM, theory shows that in certain situations the current-induced torques can cause the magnetization of a ferromagnetic layer to spin around, or precess, at a frequency controlled by the current. Even more possibilities arise from adding an additional ferromagnetic layer that allows for additional forms of torque. These effects raise the possibility of three terminal devices in addition to the two-terminal devices typically designed using spin-transfer torques. Recent excitement has emerged in this field from the discovery that spin-orbit coupling, the coupling between electrons' spins and their motion, provides new mechanisms for switching the magnetization. switching between parallel to anti-parallel alignment) by these spin-transfer torques is leading to increasing use of such devices in integrated circuits. The ability to control the state of MRAM devices (e.g. A large current can generate a torque big enough to change the bulk magnetization direction of the material it is passing through. This effect is known as a вЂњspin transfer torqueвЂќ. When an electron with misaligned moment passes into a magnetized material, the mismatch (misalignment) gives rise to a small twisting force - a torque - between the electronвЂ™s spin and the bulk magnet. There is an additional effect by which the current doesn't merely respond to the magnetization of the layer but actually disturbs it. Such devices form the basis for magnetic random access memory (MRAM). Magnetic tunnel junctions store ones and zeros in the different alignments (parallel and antiparallel), and that information can be simply read by measuring the resistance. Electrons can tunnel through this barrier to conduct electricity, but the resistance depends on whether the magnetizations in the two layers are parallel or antiparallel. In these devices, two layers of a ferromagnet are separated by an electrical insulator that is only several atomic layers thick.

Magnetic tunnel junctions makes use of this effect. For example, an electric current flows more easily through a ferromagnet if the spins of the flowing electrons are aligned with, rather than opposite to, the magnetization. Because individual electrons also have an intrinsic magnetic moment вЂ“ which is often referred to as the electron вЂњspinвЂќ - they can interact with ferromagnets in some unusual ways. A current (white arrow) flowing through a tantalum film generates a current of spins (dark blue arrows) that impinges on the ferromagnetic cobalt iron boron layer and causes the magnetization (gold arrow) to charge directions (light blue arrow).ДЄ ferromagnetic material such as iron acquires its magnetization because the magnetic orientation of its constituent atoms all line up in the same way.

Spin orbit coupling