Applied Materials Inc and Tokyo Electron Ltd said on Monday they have given up plans to merge in a deal that would have been worth more than $10 billion, citing problems in getting approval from U.S. antitrust regulators. U.S.-based Applied Materials had agreed in September 2013 to buy Tokyo Electron in an all-stock deal combining the world's No.1 and No.3 makers of chip-making gear as demand for their products slows and turning a profit becomes tougher.