  As an emerging non-volatile memory technology, magnetic random access memory
(MRAM) has key features and advantages including non-volatility, high speed,
endurance, low power consumption and radiation tolerance. Conventional MRAM
utilizes magnetic tunnel junctions (MTJs), which consist of two ferromagnetic
layers separated by an insulating tunnel barrier. The orientation of the
magnetic layers represents the binary data (0 or 1), and electrical resistance
changes depending on the relative orientation of these magnetic layers. Despite
these advancements, the quest for a swifter, more stable magneto-resistive
random-access memory paradigm persists. In this vein, we present a
groundbreaking development: room-temperature antiferromagnetic tunnel junctions
devoid of any net magnetic moment. Over 200% tunneling altermagnetic resistance
(TAR) ratio was measured at RuO2 (110)/MgO/RuO2 (110)/W structure, which is
achieved by changing the antiferromagnetic Neel vector of RuO2 with an ultralow
current density 2 MA*cm-2.
