<a href="https://somedomain.com/api/doc/somefile.pdf" ng-click="openPdf($event)">PDF</a>

function openPdf($event) {
    // Prevent default behavior when clicking a link
    $event.preventDefault();

    // Get filename from href
    var filename = $event.target.href;

    $http.get(filename, {responseType: 'arraybuffer'})
    .success(function (data) {
        var file = new Blob([data], {type: 'application/pdf'});
        var fileURL = URL.createObjectURL(file);

        // Open new windows a show PDF
        window.open(fileURL);
    });
}