Magneto-Electric Spin-FET Voltage Control
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Solution Overview
Problem
Current spintronic devices face challenges in achieving non-volatile, low-power magnetic memory elements with efficient voltage control, as they require large current densities and complex schemes involving magnetic fringe fields or high-current-density pulses, which are inefficient and power-intensive.
Innovation Solution
The development of a magneto-electric spin-FET using Cr2O3 or similar materials as a gate dielectric, which induces a voltage-controlled interface magnetization to polarize the channel conductor, enabling non-volatile, low-power switching of magnetic states without the need for external magnetic fields or refresh currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic spin valves or magnetic tunnel junction structures are used for magnetic memory elements, then magnetic state control is achieved, but large current densities and complex schemes involving magnetic fringe fields are required
Solution Approach 1:
The patent replaces the conventional spin-torque transfer mechanism (which requires high current densities) with a magneto-electric field effect mechanism. A gate voltage applied to a magneto-electric material (such as Cr2O3) induces an interface polarization that generates a magnetic field, which in turn controls the magnetization state of the ferromagnetic layer. This substitution of the control mechanism eliminates the need for large current densities through the memory element itself.
Solution Approach 2:
The patent introduces a magneto-electric material (e.g., Cr2O3) as an intermediary between the electrical gate control and the ferromagnetic layer. The gate voltage first induces interface polarization in the magneto-electric material, which then generates a magnetic field that acts on the ferromagnetic layer. This intermediary mechanism allows indirect control of magnetization without requiring high currents to flow through the magnetic layers.
2Reliability
If spin-torque transfer memory elements are used, then magnetic switching is achieved, but high-current-density pulses are required
Solution Approach 1:
The patent replaces the spin-torque transfer mechanism (which requires high-current-density pulses) with a magneto-electric field effect mechanism. Instead of using spin-polarized currents to exert torque on the magnetization, the invention uses a gate voltage to induce interface polarization in a magneto-electric material, which generates a magnetic field that switches the magnetization state. This substitution dramatically reduces power consumption by eliminating the need for high-current pulses.
3Reliability
If conventional magnetic memory elements are used, then memory functionality is achieved, but refresh power is required
Solution Approach 1:
The patent changes the fundamental parameter of magnetic state control from current-based (spin-torque) or field-based (fringe field) methods to voltage-based magneto-electric field effect control. By applying a gate voltage to the magneto-electric material, the interface polarization and resulting magnetic field can be precisely controlled. The magnetic state is maintained as long as the gate voltage is applied, enabling non-volatile memory functionality without requiring refresh operations.
4Reliability
If magnetic fringe fields are used to write memory elements, then magnetic state writing is achieved, but complex schemes are required
Solution Approach 1:
The patent extracts the magnetic field generation function from the conventional fringe field writing scheme and relocates it to a magneto-electric material positioned adjacent to the ferromagnetic layer. Instead of using external magnetic fields or complex fringe field arrangements, the gate voltage applied to the magneto-electric material directly induces the necessary magnetic field at the interface. This simplifies the writing scheme to a straightforward voltage control mechanism.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for reliable isothermal switching of magnetization at room temperature, achieving high magneto-resistance ratios and combining memory and logic operations in a single device with reduced power consumption and no need for external magnetic fields or refresh currents.
Implementation Method 1
a magneto-electric substrate; materials where an applied voltage induces a magnetic moment and where the interface polarization is large
Implementation Method 2
the voltage controlled interface magnetization to polarize the channel conductor
Implementation Method 3
achieving high magneto-resistance ratios
Data Source
AI summary
The invention relates to a magneto-electric spin-FET including a gate film of chromia and a thin film of a conductive channel material which may be graphene, InP, GaAs, GaSb, PbS, MoS2, WS2, MoSe2, WSe2 and mixtures thereof. The chromia, or other magneto-electric, and conduction channel material are in intimate contact along an interface there between. The resulting magneto-electric device may be voltage-controlled and provide non-volatile memory.