1. A switchable junction element ( 600 ) having an intrinsic diode ( 634 ) formed with a voltage dependent resistor ( 640 ), comprising: a first electrode ( 618 ): a second electrode ( 622 ); a memristive matrix ( 620 ) configured to form an electrical interface ( 630 ) with the first electrode ( 618 ), the electrical interface having a programmable conductance; and the voltage dependent resistor (VDR) ( 640 ) in electrical contact with the memristive matrix ( 620 ), the voltage dependent resistor being configured to form a rectifying diode interface ( 628 ) with the second electrode ( 622 ).