His name was Akor Doomflayer and the battle took place on Armageddon
The only information I was able to find on Akor and his battle with Logan was in Logan Grimnar's Lexicanum entry, I'll bold the relevant parts :
Logan Grimnar's chosen weapon is a trophy of war, prised from the cold dead hands of a powerful champion of the Dark Gods. It was upon the battlefields of Armageddon that the Great Wolf won his fabled axe, amid the blood and fire of the battle on the banks of the River Chaeron. After hours of bitter fighting, the river ran red with blood and the bodies of Cultists and traitor Guardsmen were piled high. World Eaters Chaos Space Marines attempted to cross the river in baroque armoured barges or over bridges melded from the bodies of screaming slaves, the traitors charging across the flesh-structures to reach the Space Wolves. Seeing a chance to turn the tide of battle, Logan Grimnar led his Wolf Guard down into the gore-clouded water to meet the berserk warriors of Khorne head-on. The Chaos Champion Akor Doomflayer charged out of the ranks of the World Eaters, his rune-encrusted axe cutting down two of Grimnar's Wolf Guard in the span of a few moments. Suddenly the Great Wolf found himself fighting for his life, Doomflayer's insane fury pushing him back toward the Imperium's defensive line. With an incoherent cry the Khornate Champion struck the flat of Grimnar's Frost Blade, shattering it into a million glittering shards. Doomflayer's moment of triumph was also his last, as the Great Wolf lunged inside his executioner's swing, ripping off his skull-faced helm with a clawed hand and sinking his fangs into the exposed throat underneath. As Doomflayer fell into the bloody river Grimnar snatched up his opponent's crimson-steel axe, cutting a path back to his Wolf Guard through knots of homicidal Khornate Berserkers. For the rest of the campaign on Armageddon Logan fought with the axe, and upon his return to Fenris he had it reforged, dubbing it the Axe Morkai.